I have to support Willy totally on this.
Even as much as I am advocating desipramine and am convinced of its efficacy, I sincerely do NOT advocate anyone currently on existing injectable treatments for MS to ever go off of them in favor of trying desipramine or any other unproven medication. No way!
Also, this might not be the best thing to do (Arron, please excuse me, because I'm truly not trying to send ANYONE away from this website), but www.msworld.org
(an NMSS associated support group board) has a very active teens with MS forum that I think you may find very helpful. Arron, if I shouldn't mention this, please feel free to admonish me or delete my suggestion. I only recommend this because their teen board is already established and has been for some time.
The folks on that board are extremely compassionate and supportive, and I think you may find (as Willy might refer to it) wonderful "warm fuzzies" and extreme compassion and sharing of experiences and difficulties. Plus, your son, I'm certain would probably come into contact with someone else of his age and similar situation to make friends with.
All the best to you!
EDIT: Oh, and I totally agree with Art, too.
Well, shoot, here's EDIT NUMBER TWO: I just bounced over to MSWorld, and lo and behold after a quick peek, there are three new kids over there. Two are 16 year olds with MS, and one is 15, and they are tickled over locating each other. Give it a shot!