"He was suffering and no one knew what was wrong with him."

Justin Bieber is about to make a big confession in his upcoming and highly anticipated documentary, dropping on January 27—and it has to do with way more than just his music.

According to TMZ, Bieber will reveal in his new documentary, Justin Bieber: Seasons, that he spent most of 2019 dealing with Lyme disease—which, for a good portion of time, went undiagnosed. Bieber also confirmed his Lyme disease diagnosis—and another diagnosis of "chronic mono"—in an Instagram post shared Wednesday.

"While a lot of people kept saying Justin Bieber looks like s—t, on meth etc. they failed to realize I've been recently diagnosed with Lyme disease," he wrote. "Not only that but had a serious case of chronic mono which affected my skin, brain function, energy, and overall health."

Bieber went on to say that everything will be further explained in his new documentary, which will air in 10 parts on YouTube. Per TMZ and their sources who have seen the documentary, Bieber endured "scary symptoms" throughout 2019. "Doctors struggled to figure out what was wrong with him, but couldn't put their finger on it until late last year," according to TMZ.

The documentary is also said to reveal that Bieber had been "battling extreme depression" during that time as well, "because he was suffering and no one knew what was wrong with him." At that time, doctors also "gave Justin a pharmacy full of medicine to combat his ailment before the properly diagnosed it, and one of the meds caused his skin to break out badly."

Bieber was reportedly diagnosed with Lyme disease in late 2019, though it's unclear how, when, and where he contracted the disease. Now, however, he is being treated with the proper medications and is on the road to recovery. "It's been a rough couple years but getting the right treatment that will help treat this so far incurable disease and I will be back and better than ever," Bieber wrote.

Hold on, what is Lyme disease again?

According to the Centers for Disease Control and Prevention (CDC) Lyme disease is the most common vector-borne (aka, transmitted through fleas, ticks, or mosquitoes) disease in the US. Lyme, most commonly caused by the bacterium Borrelia burgdorferi, is transmitted to humans through the bite of infected blacklegged (deer) ticks.

What are the symptoms of Lyme disease?

The initial symptoms include fever, headache, fatigue—most of which mimic the flu, which makes Lyme disease difficult to detect and diagnose.

A characteristic skin rash called erythema migrans, which looks similar to a red bull's-eye, may also show up—but only occurs in about 70% to 80% of all those infected with Lyme disease.

If those initial symptoms aren't caught early enough, Lyme can spread throughout the body, to places like the joints, heart, and nervous system, resulting in more serious symptoms such as facial paralysis and arthritis, per the CDC.

So, how is Lyme disease treated—and how can it be prevented?

When caught early, most cases of Lyme disease can be treated successfully with a few weeks of antibiotics like doxycycline or amoxicillin. However, individuals with more advanced stages of Lyme disease—like neurological or cardiac forms of the illness—may require intravenous treatment with antibiotics such as ceftriaxone or penicillin.

The CDC says most people infected with Lyme will recover when treated within a few weeks of antibiotic treatment. However, symptoms of fatigue and muscle aches may persist in a small percentage of people for over six months—this condition is called Post-Treatment Lyme Disease Syndrome (PTLDS), also known as chronic Lyme disease.

The best ways to prevent Lyme disease, according to the CDC, is protecting yourself against tick bites. Always use insect repellent when heading outdoors -- especially in tick-infested areas. Additionally, check your body for any ticks, removing them promptly. If your property is prone to ticks, you can also use pesticides to control the tick population.