If you look on Facebook, there are some really great closed groups for chronic pain support. I myself have chronic pain and love the groups I'm a part of. I would suggest joined a closed group and not an open group so that he can have some privacy and not have to worry about people he knows on Facebook reading his posts.

Hi, My husband suffers from chronic pain, back, shoulder, knee..... Can anyone refer us to a good online support board?
Thanks!