Hi K.,
I have a good friend who suffers from the same social anxieties. He can't go to the grocery store alone. He can't go anywhere new without an "emotional anchor," which means a close friend he feels safe with.
He is currently in therapy for the first time and I feel that this with the combination of medication will eventually help him to lead a more normal life.
He is able to hold down a job, but this is one he got with the help of one of his "emotional anchors," like I said.
He'll spend hours alone in his room and he can't sleep most nights and he can't go places where there are lots of people and he can barely walk down a busy street alone.
I don't know if any of this sounds familiar, but my suggestion is that your son needs psychological help before he can make any real plans for the future.
I don't know what triggers this kind of behavior in a person, usually a traumatic event. For my friend, it was depression and failing out of college.
Try your best to be supportive, this may take a while, but in the end he's less likely to have an anxiety attack on the way to a job interview, or something similar. Sometimes when things like that happen, they only tend to make the person want to be more withdrawn from embarrassment.
He is probably aware that his behavior is strange and abnormal and as much as that bothers him and as much as he knows it bothers the people he loves, he doesn't have much control over it.
I don't know how much this has to do with his ADHD. Lots of people have attention disorder issues and still lead normal lives off medication. It would certainly help to quiet the noise in his head, if he really does have that, to take some type of medication. But it doesn't look like that is his real issue.
Be patient. Tell him that you love and accept him no matter what and that you want to help him feel better about himself.
He's only 18. I know that sounds strange, but some people don't figure out where they're going until they're in their 30s. Forcing him to grow up won't change how he is. (I know, my friend with social anxiety is 30.) Helping him to work through this will help him to lead a better life in the long run.
Just my thoughts. Hope this helps.
C.