The shoulder problem was similar for me.

For many years I have used very cheap Microsoft ergonomic keyboards (discontinued some years ago), which were already much better for the position of the arms than standard keyboards.

Then I switched to a truly split keyboard, which is even better.

I have also switched to Dvorak a few years ago. A couple of months were needed until recovering and then exceeding the previous typing speed, but it was worthwhile, because the comfort of typing has greatly improved. Now I regret that I have not done this earlier.