Hillary Clinton released a letter from her doctor last year that said she was in 'excellent physical condition,' outside of a hypothyroid condition and history of prior blood clots.

But some of her political opponents have questioned her health, and Trump, 70, has been suggesting on the campaign trail recently that she lacks the physical fitness required of a president.

Photos of Hillary propping herself up against stools, pillows and tables during a number of speeches and public appearances in recent weeks tell a different tale and have revived claims from Donald Trump and his supporters that she lacks stamina on the campaign trail and may be suffering from health issues.

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Photos of Hillary propping herself up against stools, pillows and tables during a number of speeches and public appearances have revived claims from Donald Trump and his supporters that she lacks stamina on the campaign trail

Hillary Clinton released a letter from her doctor last year that said she was in 'excellent physical condition,' outside of a hypothyroid condition and history of prior blood clots

The hashtag #HillarysStools caught fire on Twitter this week, after a Trump supporter posted a montage of images of Clinton, 68, leaning on or sitting on stools during campaign stump speeches.

In other photos, Clinton speaks at a podium with the ubiquitous stool close behind her.

Other sharp-eyed internet sleuths have also found images of Clinton supporting herself against on tables, chair backs, and even her staffers while out and about.

On Wednesday, the publication Heat Street posted an array of photos of Clinton propping herself up on pillows while seated, noting that the presidential candidate included requests for supportive back pillows in paid speaking contracts.

'Once you see [the stools], you can't stop noticing,' wrote Trump supporter and blogger Mike Cernovich on Twitter. 'Sick Hillary has one everywhere, can't stand on her own for long!'

'When #HillarysStools not available, find next closest thing for leanin--such as a rail, chair, or table as seen here,' wrote another user, posting a video of Clinton leaning on a table, a chair and a railing while visiting Scranton, Pennsylvania with Joe Biden.

'Once you see [the stools], you can't stop noticing,' wrote Trump supporter and blogger Mike Cernovich on Twitter. 'Sick Hillary has one everywhere, can't stand on her own for long!'

Another user tweeted that 'Every picture of sick Hillary has a hidden stool nearby. She can barely stand.'

Sean Hannity showed a photograph of Clinton holding on to two aides for assistance while walking up the stairs, and asked Fox News medical experts to evaluate it

Another user tweeted that 'Every picture of sick Hillary has a hidden stool nearby. She can barely stand.'

The Drudge Report, which has long publicized stories that claim Clinton is in poor health, made the pillow story its top banner on Wednesday, with the headline 'Pillows for Hillary.'

Clinton 'lacks the mental and physical stamina to take on ISIS,' said Trump in a speech on Monday. He also said Clinton often 'gives a short speech then she goes home, goes to sleep, she shows up two days later.'

Clinton's campaign pushed back sharply on the health claims, calling them a 'deranged conspiracy' in a statement to reporters.

'Donald Trump is once again peddling deranged conspiracy theories in a desperate attempt to change the subject – this time with absurd and debunked claims about Hillary Clinton's health,' said the campaign. 'This is hardly the first time Trump and his allies have donned tin foil hats when things weren't going his way.'

Sean Hannity also devoted several episodes of his show last week to highlighting claims about Clinton's health, such as whether she suffers from neurological issues related to a 2013 concussion.

Hannity showed a photograph of Clinton holding on to two aides for assistance while walking up the stairs, and asked Fox News medical experts to evaluate it.

'[I]f she's prone to falling, you can see from that picture up there that it looked like she can barely get upstairs without two people carrying her. Guess what if she falls and hits her head? She'll get a blood-clot,' said medical correspondent Dr. Marc Seigel.

Dr. David Samadi, another Fox News medical correspondent, said the photo 'speaks a million words.'

'Is she fatigued? Is she dehydrated? One of the main reasons she fell in 2012 and had the concussions was severe dehydration,' he said. 'They're holding her and going up the stairs. So she may be really dehydrated, she may have arthritis, she may have back pain, she may have fallen again. We don't know.'

Others say there might be a more benign explanation for Clinton's penchant for leaning and sitting on stools during public appearances.

Dr. David Samadi, another Fox News medical correspondent, said the photo 'speaks a million words'

Dr. Drew Pinksky, a celebrity doctor and internist, said that he and one of his colleagues evaluated Clinton's doctor's letter and were 'gravely concerned, not just about her health, but her healthcare'

'A very reasonable explanation would be that Ms. Clinton has a grueling schedule, spends a great deal of time on her feet meeting and greeting and speaking, and that she gets tired,' Dr. David Blumenthal, an expert on presidential medical history, told the Daily Mail Online. 'Another hypothesis: it makes her look relaxed when she sits.'

Blumenthal said he could not comment directly on Clinton's health because he has not reviewed her medical history. He said he does not recall this coming up as a health issue for past presidents.

'I don't recall this particular issue arising as an indicator of the health status of presidents,' he said.

While some medical professionals have cautioned the public about evaluating health issues based on photos, they say there are some reasons to be concerned based on the information released in Clinton's doctor's letter.

Dr. Drew Pinksky, a celebrity doctor and internist, said on KABC on Tuesday that he and one of his colleagues evaluated Clinton's doctor's letter and were 'gravely concerned, not just about her health, but her healthcare.'

He questioned the blood thinning medications she was prescribed by her doctors, calling them extremely outdated, and noted that she suffered from an 'exceedingly rare' type of blood clot known as a deep venous thrombosis after her 2013 concussion.

'I've only seen one of these [types of blood clots] in my career. It essentially guarantees that somebody has something from with their coagulation system,' he said.

Photos of Clinton have sparked questions about her age and fitness in the past.

In a 2014 photo for the cover of People magazine, critics said Clinton appeared to be holding onto an 'old person's walker.' However, she was holding onto a chair.