I believe there are medications to relieve itching.

He might consider an emergency visit in a phychiatric hospital. It might be hell in his condition but I believe the success rate at getting people stabilized is pretty good. I would consider plan A to be finding the right mix of medications.

I think I was able to do better when I finally accepted the idea that I might never get rid of this thing. I still fight it tooth and nail but acceptance is important.

If he has a computer you might encourage him to come here.