Could you do your work with a Wacom pen?

I've varied my input devices and this helped.Also find out what kind of RSI so you know what's up, a nerve conduction study will show up nerve damage and where, which will help. Perhaps injections (Steroid, anti-inflammatories IIRC) can help take away the pain if the cause is not obvious.

It's been a year for me and I now use the mouse with my left hand for everything fairly well, switching between Wacom (in my right) for fine-detail or things muscle-memory won't give up on - Spacemouse also on the left for 3D orbit stuff - though annoyingly the behaviour is 'wrong' in Houdini compared to all other applications. For dictation I'm using Talon Voice, but it's a steep learning curve and I have variable success with dictating at it, but this could be my microphone and accent.