Well - OCD is a type of anxiety - so is he getting any treatment for that?
Social skills deficits are common in schizophrenia (even when using medication) and (in addition to anxiety - another factor possibly) you can help counter that with social skills training. Schizophrenia seems to negatively impact the part of the brain that deals with social understanding (the researchers call it “social cognition” and related “theory of mind”. Added training in these areas seems to help with improving sociability / friendships.
A story of one person’s experience:
Here is some more info:
and
a book that you could buy and get a local social worker or therapist to work with your son on: