Just in case this helps anyone:
I didn’t have RSI, but as I approached 70, I started getting arthritis in my hands and wrists that sometimes made keyboard work unpleasant.
My doctor gave me a prescription for a cream with a very high dose of THC and CBD that worked like magic for me. If I stop using the cream, a month later the discomfort returns. As far as I know, this external use cream has no bad side effects. Talk with your doctor.