In reply to zmv:
I've had this problem. In fact I still have this problem. Dr believes it is early onset arthritis. I stopped climbing completely last year, and it's still not resolved, and is now effecting my MTBing (and doing anything that requires me to grip something for a longish period.
I think it was caused by years of putting up with it, strapping fingers and carrying on climbing.
Hope your issue is nothing like mine, but would be interested if you do dig up some expert that I could get a third opinion from.