(CNN) From Donald Trump and his top surrogates to the right-wing media and its engine rooms of outrage in the blogosphere, Hillary Clinton's opponents are ramping up efforts to sow doubt over the candidate's health.

The campaign -- which goes back years -- has escalated to shouting over the summer, as Trump spiraled in the polls while mostly failing to connect with voters outside his base demographic. Now, as the race enters a crucial phase, there has been a growing push to fundamentally undermine Clinton's candidacy.

Much in the way "birthers" (Trump was among the most prominent) sought similar ends by questioning President Barack Obama's citizenship, the "healthers" are using junk science and conspiracy theories to argue that Clinton is suffering from a series of debilitating brain injuries.

In an interview on "Fox News Sunday" this weekend, former New York City mayor and Trump surrogate Rudy Giuliani first accused the mainstream media of hiding evidence, then encouraged doubters to "go online and put down 'Hillary Clinton illness.'"

There is absolutely no credible evidence to backstop any of these claims, including on the "videos" Giuliani cited. Clinton's physician -- the only person to speak on the record who has actually examined her -- has repeatedly affirmed the former secretary of state's health and fitness for the highest office in the land.

During an appearance Monday night on the Jimmy Kimmel show, Clinton called the GOP claims about her health a "wacky strategy."

"I don't know why they are saying this," she said. "I think on the one hand, it is part of the wacky strategy, just say all these crazy things and maybe you can get some people to believe you."

But for those who want to believe, the structure of the lie borders on impenetrable -- baked into its "medical" assertions is the tightly held belief that the press is in cahoots with Clinton, protecting her political prospects by working overtime to hide her imagined ailment.

The facts, though, tell a very different story. This is it.

The roots of the health conspiracy theory go back to late 2012

In a bit of dark irony, Clinton's political opponents then, most notably the Republican former U.S. Ambassador to the United Nations John Bolton, suggested that Clinton was faking it -- that the secretary of state, as Bolton put it, had come down with a "diplomatic illness" in order to avoid the congressional inquiry.

In the weeks after the injury, Clinton would be hospitalized and prescribed blood thinners to dissolve a blood clot located in a vein behind her right ear. The diagnosis was made during a follow-up exam related to her concussion. The clot did not, per Clinton's doctors, result in a stroke or any other neurological complications.

On January 23, 2013, a little more than a month after she was first slated to appear before Congress, Clinton testified at length to Senate and House committees about the Benghazi attacks.

Karl Rove helped plant the seeds in 2014

In May 2014, more than a year after Clinton left the State Department, Republican strategist Karl Rove made headlines by suggesting Clinton had suffered brain damage in 2012.

"Thirty days in the hospital? And when she reappears, she's wearing glasses that are only for people who have traumatic brain injury?" he said, according to a New York Post report . "We need to know what's up with that."

Rove would attempt to walk back his comments a day after they were made public, telling Fox News of the brain damage comment that he "never used that phrase."

He also conceded that Clinton had not, as he first said, spent a month in the hospital. She was there for about three days. Politifact also slapped a "False" tag on Rove's claim that Clinton's prismatic glasses indicated her injuries had been worse than initially let on.

The talk would mostly die down over the next year. In July 2015, Clinton's longtime physician, Dr. Lisa Bardack, delivered her a clean bill of health

"(Clinton) had follow-up testing in 2013, which revealed complete resolution of the effects of the concussion as well as total dissolution of the thrombosis," Bardack wrote. "Mrs. Clinton also tested negative for all clotting disorders."

The alleged 'seizures'

The rumors have traveled with remarkable speed through the pipeline connecting small conservative and right-wing blogs to larger outlets like Breitbart, Infowars and Fox News.

First, there was the muffin shop.

During a June photo op in Washington, Clinton turned back reporters' questions with what AP correspondent Lisa Lerer in a first person account titled "Video proves Clinton suffering seizures? Not so, I was there," described as "an exaggerated motion, shaking her head vigorously for a few seconds."

"After the exchange," Lerer wrote, "(Clinton) took a few more photos, exited the shop and greeted supporters waiting outside."

Hillary's having seizures? Not quite. My trip into our conspiracy-fueled election cycle. https://t.co/rJUYSz6997 — Lisa Lerer (@llerer) August 12, 2016

End of story? Not quite.

More than a month later, pro-Trump blogger Jim Hoft picked up the video and, on his Gateway Pundit site, ran a headline blaring, "Wow! Did Hillary Clinton Just Suffer a Seizure on Camera?" She had not, of course, as had been clear to everyone present. But the video soon went viral. Less than a week later, after Clinton delivered her convention address, he was back at it, publishing a GIF of the nominee's amused face (there were a lot of balloons falling) under a similar title: "Wow! Media Missed This=> Did Hillary Suffer Another Seizure After Her DNC Speech?"

In the coming days and weeks, conservative media and the Trump campaign itself began to pick up the thread. Fox News host Sean Hannity, an unabashed supporter of the GOP nominee, dove in with particular gusto, gathering panels of "experts" to examine video clips of Clinton coughing and, again, batting her head at the D.C. muffin shop.

None of the physicians convened by Hannity had examined Clinton and at least one, Fox News medical correspondent Dr. David Samadi, is a urologist. When an actual neurologist, Dr. Fiona Gupta, joined the group, she mostly dismissed Hannity's questions, saying, "It's just so hard to speculate based on snippets (of video)."

When he pressed on ("It almost seems seizure-esque to me"), another Fox News contributor, Dr. Marc Siegel, an internist, pushed back.

"Well I'm not a neurologist," Siegel said, "and I don't think that necessarily looks like a seizure."

The 'fall'

At around the same time Hannity was hosting his panels, a blog called the American Mirror and the Drudge Report gave a boost to a photograph that had been floating around for months. Taken back in February, the image shows Clinton being helped up a flight of stairs outside a halfway house in in North Charleston, South Carolina.

"The questionable health condition of Hillary Clinton should be a major issue of the 2016 campaign," the American Mirror post begins. "The latest evidence comes in the form of Clinton being helped up a set of stairs by multiple individuals outside what appears to be a home."

But the Getty Images photo caption -- filed months earlier -- tells a very different story.

It reads: "Democratic Presidential candidate, former Secretary of State Hillary Clinton slips as she walks up the stairs into the non-profit SC Strong, a 2 year residential facility that helps former felons, substance abusers, and homeless move into self-sufficiency."

The "syringe" and fake medical records

As the conspiracy theories took flight, boosted by Trump's repeated assertions that Clinton is too chronically tired or weak to handle the White House workload, "questions" from right-wing bloggers and gadflies about Clinton's security detail began to focus in on a single piece of equipment carried by one agent.

On Twitter and on assorted blogs, conspiracy theorists began to focus on images they believed to show, as one headline put it, "Hillary's Handler Carrying Auto-Injector Syringe For Anti-Seizure Drug Diazepam."

Secret Service agent was carrying an auto-injector with Diazepam pic.twitter.com/6d3B5mmaOe — Azusa (@PositiveInt) August 8, 2016

But again, this was simply not the case. Hannity broadcast the story to his millions of viewers, citing the Gateway Pundit and its sources, with no evidence of his own.

Indeed, the Secret Service has weighed in repeatedly when asked. On Monday morning, spokeswoman Nicole Mainor dismissed the report in an email to CNN.

"The item in the Detail Leader's hand is a flashlight," she said.

The rumors took a more serious turn around this time, when a since-deleted Twitter account called @HillsMedRecords shared what purported to be leaked medical record showing Clinton having been diagnosed with early-onset dementia. Snopes.com, a fact-checking website, quickly snuffed them out and Clinton's doctor -- whose letterhead was used in the images featuring the fake reports -- put out a statement explaining that the documents are "false, were not written by me and are not based on any medical facts."

The Trump-Breitbart connection

Breitbart News has been a house organ for Trump since the early days of his run, but the union became more formal last week when the media company's executive chairman, Steve Bannon, was hired as campaign CEO.

It has also been among the most consistent and highly trafficked peddlers of the conspiracy theories surrounding Clinton's health. When she was slightly late returning to a debate stage in December -- there had been a hold up entering the bathroom -- Breitbart published a story weeks later citing "a law enforcement source with inside connections" who said Clinton "was missing from the stage due to health issues stemming from a previous brain injury."

Trump himself has begun to allude more and more baldly to these suggestions, most notably in a pair of speeches last week when he questioned Clinton's "mental and physical" stamina. On Friday, he tweeted : "#WheresHillary? Sleeping!!!!!"

All this as Drudge doubled down by bannering its site with an absurd Heat Street post, titled, "MUST SEE: Photos of Hillary Clinton Propped Up on Pillows." The images, with arrows superimposed to point out the pillows, show Clinton -- fully alert, engaged, sometimes addressing large audiences -- in the presence of small pillows that she sometimes placed behind her back when she was seated.

By the end of last week, at least one prominent Republican Trump supporter had heard about enough. After "Fox and Friends" played a clip of Dr. Drew Pinsky, of "Celebrity Rehab" semi-fame and HLN host, discussing his "grave concern" for Clinton, former House Speaker Newt Gingrich lost his patience

"With all due respect to television doctors, when you have a doctor who has never seen the patient begin to give you a complicated, fancy-sounding analysis based on what?" Gingrich said.

"I mean, I would be very cautious and I would recommend to doctors for professional reasons to be very cautious deciding you're going to start analyzing people."