if it's pills why is he in the bathroom a lot and for a long time?
my ex used to lock himself in the bathroom forever. I would ask him if he was ok and he would get pissed like I'm crazy because I cant even leave him alone in the bathroom. Uh, excuse me... there is only one bathroom and you've been in it for over one hour. Anyways, he was in there shooting up heroin. I would find weird brown stains around the sink, foil in the trash, balloon pieces, etc.
my ex also dozed off randomly, in the middle of conversations, glazed droopy eyes ... He blamed it on allergies. Which is BULL! Because after these *allergy* episodes, I'd find needles somewhere and tract marks on his arms.
You are not wrong. You know what is happening and you dont need him to admit it.
I feel sorry that you are in this situation. The detective stage is sooo stressful and worrisome. Confront him and tell him to do something or else you get out. Nobody should live like this.