I went through the same thing. Sounds like he may be struggling with chemical dependency. (opiates) such as Heroin, OxyContin, Percocet, ect. I've struggled for 3 years, and am now finally on the suboxone treatment plan. What he was most likely experiencing was opiate withdrawals. You shake, get the sweats, get cranky, tired, weak, a fever, nausea, and your whole body is in pain. It's absolutely awful, the worst thing I've ever experienced in my entire 21 years. Perhaps when he hurried out he had a chance to shoot up and overdosed. It's hard to say, and if you really want to know what happened all you can do is ask. Opiate addiction is very hard to deal with and it's a long battle, you have to fight hard. The user must want to stop and change, nobody can make them. Personally for me, narcotics anonymous only helped to meet new hooks, outpatient treatment isn't strict enough, inpatient, well I've never done it. But when I was reffered, that was my que to stop. I cleaned up, changed my number, and stopped talking to people that enabled me. I stayed clean for 6 months, and for the next 6 months up until a month ago I was shooting up half a gram of heroin a day. I couldn't bare withdrawals because my tolerance had gotten to high and I was once again physically addicted to heroin. I found a doctor, and now I'm on suboxone. It's saving my life. You need to sit down with him and have a serious talk. Good luck.