@kajlang I just saw your post, and hope that your son is still in the hospital and they find the right medication for him.
The court system, for me, was the key to getting my daughter successfully medicated. After her arrest, I went to her arraignment (where normally they don’t speak to anyone in the “audience”) and approached the officer in charge and told him I had vital information for the judge. I was allowed to speak and made it clear she was psychotic (“My daughter speaks to people up there and can read your mind”) and that she needed medicaton. When the judge later transferred my daughter to a psych hospital, I faxed a one page doc to each of the three places she might have been sent telling them what antipsychotic had proven the best (in her case it was a haldol dec shot given on an earlier forced hospitalization) and asking that it be given to her again.) I had NO idea which hospital she was in, and no one would tell me. However, within a few hours I had a phone call from a nurse telling me the doctor wanted me to be her health care proxy and authorize the shot. In my state, someone is assigned by the doctor/court to legally authorize care while the patient is in the hospital. That role disappears when the patient is released. So I only had say so to talk to the nurses while she was in the hospital and authorize that one shot. After she was released, I again had no power over her. I am lucky that I asked the judge earlier for her to be medicated, that he made medication a part of her release, and that the hospital read my fax. Also lucky that the 2nd court ordered injection was given to my daughter, with anosognosia, who didn’t want to take it, but had to because the Sheriff’s Office called her and came by to see her at home. Then the court order wore off as charges against my daughter were dropped. BUT she, by then, was in a sort of habit to take it, and just went with me to the doctor to get her 3rd shot the next month, and has been going ever since.
Good luck navigating the system.