I thought I'd post about my similar experiences and problems I have had from computer use and problems I still have now.
I have always been a very heavy computer user, I started learning to program when I was about 10 years old and spent every hour I could on the computer. At that time I used to use the computer by kneeling underneath a coffee table. I had problems with my knees for a few years after but then it went away and not really had any problems like that since. Also I'm sure my computer use caused me the need to wear glasses

Now onto a problem similar to you are described, which I personally would not refer to as RSI. I started getting a lot of problems with my upper back, from being hunched over a keyboard all day at work. I think part of the problem was the seating, but I could just never get comfortable. It would get so bad that I would have to quit the job, and even then I would have pain in my upper back and would be constantly trying to stretch it. This went on for a year or so, with me constantly having a bad back, doing a job for a bit (temp jobs, typing all day doing data-entry) then having a rest and going on JSA until eventually felt I had to go back and earn money again. These jobs don't give people proper breaks and I also blame that as one of the reasons. I felt like I would have to endure problems of that nature and they would only get worse so tried to stop doing that type of work, where I was sat all day using a computer, or jobs where I was free to take a break.
One of the ideas I came up with to help was to strengthen my back muscles. I felt like I had some curvature of my upper spine and that having stronger back muscles would help me sit straighter and pull my shoulders squarer. I trained myself to do handstand pressups and balance handstands and developed a lot more strength in my back which I think helped. At that time in my job I was allowed to take breaks whenever I want, and I was doing varied things and not stuck constantly on a computer, although was on one most of the time so didn't really have any problems.
I think if I had to go back to doing that same level of computer usage that my problems would return again. Since I was made redundant from my main job, I did other work after but not anything where I was stuck constantly on a computer.
So just to give you some hope that it is not necessarily permanent, I suffered horrendous problems for years, but haven't had any problems at all recently. I would make sure you take proper breaks, have proper seating, rest if appropriate from that type of work, or cut it down and try some back strengthening exercises or some yoga.
I do have a type of RSI injury which was probably caused ultimately from a complete lack of strength in my wrists/arms. This occurred before I strengthened myself up a bit, but I was lying down and playing a game on the xbox with my hands in an unusual position, then something happened and I got a tremendous pain in my wrist, and couldn't move my wrist for a second. My Ulna bone and moved up 1 or 2 mm, the pain eventually subsided but I still get problems with my left wrist from time to time and cannot twist open a jar with my left hand without encountering significant pain. This injury is probably most likely a tear of the Triquetral Fibro-cartlidge complex connecting the ulna to the Triquetral bone in the wrist, or possibly some other wrist ligament damage instead.
I have a tested touch typing speed of 75wpm at agencies, but can audio type closer to 100wpm and with several practice runs and on a laptop keyboard can do a typing test 120wpm+. All this for years and the xbox controller does me most damage to my wrists. I can sit on a computer now and type and I have no problems, I am just very wary of ever doing a job like that again which will cause me so much uncomfort. Coming home from a 9-5 computer job, then spending 5-2am on one at home probably didn't help either