It is hard to have enough information regarding a person to give advice on which kind of school to go to, but have you considered a public school or online public school and then use the tuition money for classes in your son's interest or activities such as scouting, sports, art etc? You may want to join these groups with him, depending on what it is.

It sounds like he could use more social groups outside of any school in order to find more kids that would be similar to him. Just an idea.