The main treatment for RSI, as I understand, is resting of the injured muscle (s).
Without that it will not improve.
Allow 3 months, 6 if it's really bad.
Pain killers will help, but are not a long term remedy as you need to get to the underlying cause.
Computer keyboards and mice, laptops especially, are the biggest culprits of this age.
But just review what you do constantly and you will soon find the cause.
There may be PT that will help, but stopping the activity is the main thing.
Look also at taking magnesium chloride, which is excellent for stopping muscle pain.
You may be dismayed by the rest time suggested, so do your own research, but the figures are based on what I was told when I eventually sought treatment. Years too late as it turned out, as I'm now beyond recovery.
I was foolish in putting up with the pain and inability to do my job properly, taking pain killers and suffering awful headaches and sore arms for years. The money was too good to lose, but in the end I probably lost more than I gained as I took early retirement when I was only 53, glad to stop work.
I hope you can learn from this!
Also try remedial massage. But STOP immediately.