Well, if you’re exhausted then it’s certainly not just coffee. Check your character screen, if you have a speed boost from stimulants, it can prevent you from sleeping. If you have none, then it’s not coffee.
It may be an actual bug. If nothing helps, upload the save somewhere and post link. Just the .sav file should be enough. You might have some lingering effect that should have worn off by now but for some reason didn’t.
If you can’t solve the problem, actually binge on coffee. Drink it until you’re no longer exhausted. It won’t help with inability to sleep, but it will make sleep obsolete (you’ll need to heal yourself in some other way). Take your vitamins, though. Coffee is unhealthy.