send him to a psychologists
Dear Dad,
You should definitely be worried that "something bad is forming." Is he using drugs? I can tell you from experience that it is possible, even though it might be the farthest thing from your mind.
It is possible that he might open up and reveal his thought and fears to you or your wife in a one-on-one session, in a comfortable, secure, setting: maybe in his bedroom with you sitting at eye level with him, and letting him talk without interrupting him, or telling him he's wrong to be feeling the way he feels. You need to hear him vent. You'll probably want to tell him that his thinking is wrong, but hold off until you've had a opportunity to mull over what he's said.
My son needed serious help years ago, and I just hoped that he would work it out on his own. Now he has serious problems with depression and drug abuse.
-Dooley
There are so many things kids can get into, who knows for sure what's bothering him. It sounds like he is having trouble adjusting to the academic demand and new social scene in high school. Have you considered having him go to a few councelling sessions just to see if there is anything he wants to get off his chest, any hurts, etc.?
It sounds like some depression and maybe anxiety about dealing with people. Have you tried talking to him about how he feels? Does everything feel uncomfortable and stressful?
I'd also recommend you have a read over my post in this thread:
http://www.medhelp.org/posts/Anxiety/anxiety-24-7-really-need-help/show/1340353