Short term I used a splint and tried to cut down on the time I as using a keyboard or mouse. Outside work, no gaming and minimal computer time. I kept this up until the pain subsided.

In parallel, I switched to a trackball instead of a mouse. Other people I know went with a vertical mouse. I got a giant mouse pad for my desk with wrist supports for both my keyboard and trackball. This is also a good time to double check your whole setup chair, desk, monitors making sure you have good posture

Try adjusting height of your desk and seating position.

I had pretty terrible problems that were more or less solved with a split keyboard (the ultimate hacking keyboard, with palm rests), allowing my wrists to rest in a more natural angle.

I guess it depends on what is the exact source of your pain though. For me, it was always pretty clear that the stained angle on a normal keyboard was the problem)

Try push-ups.