You don't say exactly what the "incident" at school was. Was your son violent? Talking back to voices? A risk to himself or others? All in all, if this was his first experience with psychosis or schizophrenia I believe it is excellent that he is receiving treatment/medication, even if hospitalization is not your first choice. The earlier a person is treated for sz, the better his chances for a positive outcome, i.e., recovery. Note that I don't say "cure." You son will probably always have to take medication for this illness, just as diabetics usually have to take insulin for the rest of their lives. But there certainly is no shame in that. Just hope that he agrees to take the medication once he is home -- that can sometimes be a real problem.
I was hospitalized for the first time in 1995. It was in a city some distance from my family, so my sister and her son were the only ones who visited consistently. I was 37 at the time. My symptoms came on slowly over years before I had an actual psychotic break. At first I hated the hospital and all the staff there. I told them to go to hell. I ended up hospitalized 18 times at a number of different facilities because either the meds weren't working or I wasn't taking them as prescribed. It took me until 2002 to realize that I was sick and out of control. And when I began to take Zyprexa, I began to recover. Yes, my weight doubled. Yes, I often slept 14-16 hrs a day. At first. Over time, my body began to adjust and my weight stabilized and I was able to stay awake longer. Now, I realize that the sleep may have been necessary for my mind and body to recover.
But, during the first two years after diagnosis, I attempted suicide 3 times. I needed hospitalization, even if I resented being there at the time. But now I know I was safe from myself there. It may be a good thing for your son to be where he is watched constantly and where someone is sure he is taking his meds every day. Don't be in a big hurry to have him back home. There will be time enough for that in the days to come.
The good news: It has been 14 years since I was diagnosed and the last year or two I have recovered significantly. I am now able to have my own apartment, after living with my parents for years. I am able to live on Social Security disability payments and a disability pension plan I had paid into at a prevoius employer.
I am feeling better now than ever before. Even pre-diagnosis. There is hope for your son -- medication, support, his own courage, and constantly working toward recovery. Don't expect him to be his "old self" any time soon, sad to say. But be there for him when possible. It will take a family effort. Best wishes to you.