I had the same issue come up with a mouse – switching to a trackball solved my problems. It allowed me to put my arm in a stationary position, and after seven years of trackball use, I don’t have any further issues with my arm.
I also use a Wacom tablet (I’m mostly 3dsmax, with a smattering of Autocad) – I’d have difficulty using the tablet as my primary pointing device, though.
Hope that helps.
