Great you have had a comeback phm, I've had a similar story. I retired in 2013, played in a haphazard way but after a gym leg injury I managed to rest for too long and weaken my arm muscles. I developed tendonosis. It was very frustrating getting constant arm pain after trying to fret notes so decided to play slide for about 18 months. It ended up being useful doing that light touch style and also trying out alternate tunings.

But this year a new physio found a postural problem was the cause. Now I do exercises each day, the arm pain is all gone and I was ready to play again. I have to stand up more often and practice not looking down so much.

Its interesting your Dr said to play more, and I learned you have to play the right way.