That sounds like alot of the behavior that I had when I was a teen. I went from being a cute athlete and student body president with straight A's to a total loser who only dressed in grunge. I got new loser friends and dropped my old preppy ones. I wound up attempting suicide and getting into drugs. Looking back, I cannot believe that my mother and the school didn't see the warning signs. I strongly suggest counseling right away. They really need to get to the bottom of what is upsetting him.