Quinton Aaron says what he believed to be a mere cold turned out to be something way more serious ... which he never would've caught had he not gotten checked out.
"The Blind Side" star -- who played the co-lead, Michael Oher, in the flick -- scared the crap out of people Tuesday when he posted a video of himself bedside in a hospital, saying he was gonna be alright ... but not disclosing what the heck was wrong with him.
Well, we got to the bottom of it ... and it is definitely much worse than a cold. Try full-blown upper respiratory infection!!!
Quinton says he'd been battling what felt like bad congestion since early May. At first, he didn't think much of it, but tells us when his symptoms carried over into June ... he went to the hospital. Doctors realized Monday his blood pressure was high, so they decided to keep him overnight for further tests.
Check out the clip for the full diagnosis ... sounds like he might've dodged a bullet by seeing a doctor when he did, and Quinton seems to acknowledge as much.
Luckily for Quinton, he tells us he's walking out of the hospital Wednesday after being treated for a few days. Feel better, QA!