Hi July and welcome...
Has your son ever had a full and complete neuropsychologist evaluation? There are some disorders that are organic and need medication (just like epilepsy, diabetes, etc.) and if the underlying physical disorder is not treated, therapy will not work.
If your son is so out of control at school that they are considering asking the hospital to Baker Act him, you need more intense intervention very quickly. If the school calls 911 and the doctors Baker Act him, you will not be able to override that decision and take him home. (The school cannot require that you medicate him but if he presents a danger of harm to self or others they can call 911 and it can spiral out of control very quickly.)
Does your son have a current diagnosis? What professional gave him that diagnosis? Did they do any testing? Is there a family history of mental illness or substance abuse?
You have joined a group of parents who have been there. My 15-year old (Eeyore in my sig) was violent and scary as a 5 year old -- so much so that we were advised to disrupt his adoption because 'he'd kill us in our sleep' -- he is now a very well behaved 8th grader, he still has his quirks and mild special needs but he is not dangerous at all. There is hope.