i too use a trackball and have sometimes almost unbearable pain in my right hand as well. im not sure but i think my new imac aluminum keyboard is adding to the problem too bc they keys arent as easy to depress.
the trackball took some getting used to but it did help for a while. im finding that its coming back though.
so i do have 2 other suggestions. do a some research on carpal tunnel and a good mouse for that and finally, something a bit more brave…
seriously look into switching to the dvorak keyboard layout instead of qwerty. 2 guys at my office use it and swear by it. i used a mirrored image of win xp through vmware on my work imac which uses dvorak and surprisingly kind of got the jist of it fairly fast. if you touch type and dont look at the keys youre even better off bc its definitely a mind thing.
all the vowels are set up on the home row for the left hand. the most used consonants are on the home row for the right hand. so most words are typed without moving off the home rows. the second most used are about the right hand home row and the third most below.
it took them about 2 weeks to get used to it and then they were just as fast. once i get my new mac book pro at home im going to switch my pc to it and try to learn dvorak precisely bc of my unbearable carpal tunnel.
when i roll my right wrist it sounds like im crushing chips in a bag. my wrist pops at least 6 times.. and does not feel good.
likewise if you find anything that helps please let me know.
im going to start doing some physical therapy at home, you can google exercises to help and im looking into a better mouse again.