Lil, I didn't think my daughter was doing anything other than pot either.
Just a thought: Our adult kids (and younger ones) hang out with kids who do what they do. If he is hanging with drug user, he is at high risk to be using drugs. There are many kinds of medications. My daughter liked stimulants. Most are not injected drugs.
Most adult kids are lazy for a reason and pot makes you lazy. Also synthetic pot could kill him, as Jabber knows.
If it were me, and I know I'm not, if I even suspected there was any pot/synthetic pot use, that would also be a dealbreaker. What difference does it make what it's called if it can cause so much damage? We, not just you, worry about them getting cold or hungry, but often we don't worry about what they put into their bodies...or we just don't want to know (I didn't want to know). I'm glad I didn't know until after she quit, to be honest.
However, we did not fund her living after we knew about the pot, which turned out to be far more than pot.
If he started acting up at seventeen, that could have been the age he first used drugs.
I'm not saying he does for sure. I'm just saying it is likely...most of our failure-to-launch kids do and that's part of the problem. Also, many of us don't find out until they are suddenly busted and we are in shock.
I hope this is not the case with your son. But I know denial isn't just a river in Egypt because I swam down it myself.
If he is dabbling a lot with anything, even pot, it may be a good idea to tell him he needs to go to rehab to get anything from you. If he is using at all, whatever it is is ruining his life. Impromptu triips to the apartment could be good. He should have no problem answering right away. "Oh, hold on, I'll be there in a minute!" is a red flag that he and his buddies are hiding stuff from you. Maybe you should have a key and just check in on him without notice. For sure it' a lack of privacy, but it could also save their lives. I used to check my daughter's bedroom top to bottom. After she broke the law, she had no privacy. Oh, the stuff we found!!
We are fighting for the lives of our children. I thought my daughter was going to end up in prison or die once I realized what was going on, although never in a million years would I ever have agreed that she was using meth. I would have gotten angry and, at the same time, laughed as in, "She's not THAT stupid." I did not believe s he stole her brothers ADHD medications either. Oh, denial, denial, denial. Her friends were all losers...that should have been my clue, but I didn't want to think MY daughter was like they were. Until I had no choice anymore.
Be mindful. Keep your eyes opened. I like you and Jabber and your son. I don't want anything bad to happen, Know what I mean??