I do alot of drafting and mousing as most CAD operators do and my right arm, elbow and shoulder are killing me after many years of abuse. So after some experimenting I have currently settled on a Logitech tracker ball type mouse.
It's definitely weird at first and takes some time to get used to but I really like it and I can sleep on my right side again. It's been a couple months and I expected my thumb to get tired but it doesn't. So there you go. Maybe give one a try.