Well, for my experience, using a good mouse and he need to ''fit' in your hand! When I was 14, I started to have some pains as described in the post, after that I never again used a cheap mouse (or a mouse that makes my wrist touch the table, the bottom of my hand must be on air), and the pain never returned! Ergonomics matter a lot!
As models there's the Microsoft 3.0v2 which I like a lot!