I had that come up midway through season 12, and after finishing that season with a bit of pain, I immediately quit TF2 and focused on other things, however I eventually was able to come back, and if properly handled, maybe it wont be a permanent deterrent to you either.
It used to be at the point where I couldn't move my arm, or pick something up, open a cupboard, without an extreme amount of pain, and my arms would randomly twitch violently, my hands moving maybe a foot and a half, and that was just December/January.
There are a few things which I did which made huge strides in being able to use a PC again. For starters I originally thought it would be a bad idea to do exercises, wrist stretches and arm stretches because it was incredibly painful, but I realized that they did actually help over time, and though they hurt at first, helped make it less painful overall and later on, (but it would be counterproductive not to take it slow at first!)
I also tried to exercise everyday, better circulation, and being in overall better shape but especially better circulation, will do wonders to help RSI.
The big things were that I changed my desk, working/playing situation, and chair to make sure it was as comfortable as possible, (that my body agreed with it as much as possible.)
I also changed my diet off of fast/junk food, on to more healthier foods.
All of these things combined helped me to really tame the pain and start to fix and heal my arms and wrists, and even though it was painful enough at the end of the season before last I had to suppress screams at times during PC use/opening cupboards/pushups, making simple changes to my daily life made recovery extremely fast.
I also took up cooking more often, and the nature of the way that I had to move my arms and body was an incredibly effective muscle therapy, small motions that were outside typing or gaming using my arms and I guess I'd speculate that using the muscles that are overworked in unison with the muscles that are unusually dormant in gaming was what helped so much there.
Moving more, being more active, eating better and most of all making sure I had a more ergonomic set up helped move me from a state where my arms would randomly violently twitch on their own in extreme pain, to being able to scrim regularly with only moderate and waning pain in around 4 months.