I have a brother and an aunt with schizophrenia. I also thought it sounded like an emerging mental illness when you were describing your son. I am also a high school teacher and I see it emerging in my students. Get educated as much as you can and get a good support system. Don't give up. Keep searching for answers and help. Teens often don't want to communicate with their parents. Make sure he gets connected with a counselor and support group where he feels comfortable. Many kids that don't get help self medicate with drugs and alcohol in an attempt to feel better and or escape from the misery.
Good luck
Su seb