TMZ has learned the Chicago rapper passing out in the middle of his live stream earlier this week was just the latest troubling sign that he's got a drug problem. We've been told Dex abuses opioids.

In case you missed it, FD literally nodded off in the middle of talking to his followers and playing music. His head began to lean forward and his lit blunt rested on his hand for a while before he finally woke back up. The disturbing scene was alarming to his fan base.

Dex later responded on the same platform, telling folks he'd simply fallen asleep because he was tired from working in the studio for so long ... and it was all much ado about nothin'.

Thing is, we're told that's just not the case. Sources say Dex was upset by the video of himself passing out and expressed a desire of never wanting to see himself like that again. The problem ... he's tried getting treatment, but always circles back to drugs.

This is how bad it's gotten for Dex -- we've learned there's someone who is always by Dex's side for the sole purpose of making sure he's coherent enough to do his job. We're also being told that, at times, there's even someone who sleeps in the same bed to make sure he's okay. His team is actively working to get him the help he needs.