Reposting, maybe it will help you as well..
I have been dealing with pain in my arms pretty much since I started my first job as a programmer (wrist, elbow, forearm pain) which is 10 years so far. I bought all the exercise tools you can possibly think of and used them on a daily basis to strengthen my arms as many opinions were saying that if it's RSI you need to strengthen supporting muscles. I have Theraband flexbar, Powerball, Armaid, Infra lamp, Resistance bands, dumbbells, Gripmaster Pro, GD Iron Grip Ext 90 (up to 90 kg hand resistance - beautiful grip tool) and of course foam rollers, trigger point balls, electric massagers etc. I tried changing diet, using PC less but nothing made a noticeable difference in the long run. I have also visited physios and chiros where the prescription was a bunch of exercises that I need to do daily but one of them even told me there is no such thing as RSI from the medical standpoint. After doing prescribed exercises it felt better for a time but it went back to the original state - I ascribe that to placebo effect. Oh and I don't want to forget about replacing mouses and keyboard for ergonomic ones and being obsessed with a correct posture.
Now my journey with TMS. I've been following RSI subreddit for several months now and a few months back one of the members shared his story about RSI and how he got cured by learning about TMS. He was a software engineer as well so I could relate to him. I immediately deep dived in youtube videos about TMS, Dr John Sarno explaining how that works, TMS healing wall where people had a same story and many times same personality which is a very important aspect. I was certain that I have it as well as it fit me like a glove. The pain disappeared by the end of the day. Now, since I know that placebo can trick my brain and reduce pain I didn't want to celebrate just yet. However it's been 3 months now and pain is reduced by 90% on my worst day. It's important to understand that it's not a one time cure that will remove pain for the rest of your life without doing any effort. The effort needs to be focused on your mind and things that you might be bottling up, anxious about, repressed rage etc. In my case, I always like to be the best, everything needs to be perfect, I worry about what people think, I don't like being late or sick and I'm very competitive. That creates a lot of psychological pressure inside me that manifests in pain in various parts of my body (typically where my brain thinks it can hurt because of old injuries or because it knows about diagnosis like RSI).
The most important bit is to genuinely believe that you have it and stop all the old exercises and treatments that you were doing to fix physiological issue and focus on the mind instead everytime there is pain and try to figure what might be worrying you. There are better resource out there so I'm just gonna toss a few so you know where to start.