Hello...I would suggest that your son seek counseling but I see from what you have already stated that he does not even keep his doctor's appointments. You can take another route and press charges against him if it is that serious. I know that it sounds drastic and harsh but your alternatives are very minimal. If you do not want to press charges, then you can still ask the police department from some assistance. They may even just talk to your son and put some fear into him. Your son is taking advantage of you and must be held accountable for his actions in some way, shape, or form.
You are headed in the right direction!!!! Much luck to you. Hang in there. Take care and Happy New Year.