Not saying this is related to your issues at all, but in case it ends up being helpful for someone - my uncle was a postman and lived with RSI for decades, early on they even gave him carpal tunnel surgery for it which just made things worse. After that, I think he gave up on doctors to a large extent but as he got older and was having more health difficulties, his daughter "made" him go see the doctor about them. Turns out he has multiple sclerosis and they now think the rsi may have been an early symptom of it.

Editing to add: I have dealt with RSI as a software developer myself. It started during a months long flare up of new digestive problems (which I didn't connect it to until later). I had to quit programming for years after being unsuccessful at finding long term relief, fortunately if I wasn't doing things that exacerbated it too much I would mostly feel fine and every once in awhile I would test things out to see if I had recovered. Close to ten years later, I found that I could begin working on the computer again and after some accidental experiments I realized that what was keeping the rsi under control was taking probiotics that I had begun taking for other reasons (and had kept taking because of the notably positive effect they had on my mood). When I stopped taking the probiotics for a few days the nerve and joint pain would start up again and recede when I re-started them. Eventually I had an antibiotic (which was not the first time in that time period I had taken antibiotics) and afterward don't seem to need the probiotic anymore <shrug>.