pianoloverus Since we don't know what's causing the problem or have any diagnosis for the injury, I don't think it's at all reasonable to suggest specific exercises Even though I'm sure your suggestion was well intentioned.
PatrickGester Doctors I’ve seen say there’s nothing wrong and just recommend rest. Unfortunately, medical support in my area is limited, and I can’t afford to travel to a private clinic at the moment.
It appears that @PatrickGester is caught between a rock and a hard place. He writes that it breaks his heart (and that is NOT good for your health) at the thought he might have to give up playing the piano. He's been to "Doctors" - though we don't know what their experience with hand and wrist pain is; chances are they don't usually work with musicians - but still - they are physicians, and I am not, but, so far, they have found no diagnosable condition, and rest has helped, after which pain resumed when PG's started playing again. He can't afford to go to a private clinic (hand specialist, etc), so what can he do?
...which does kind of point at a technical problem, invisible to PG, that is a potential cause.
Without going into all the specifics, if someone like PG were to come to me (and I cannot speak for my Feuchtwanger colleagues, only for myself though I believe we would approach this situation similarly),, after verifying what I could of the medical diagnosis and that the person was cleared to play by his/her doctor I would have them play for me watching very carefully everything from their seat (i.e., how they sit) at the instrument, how they held (or didn't hold) their hands, how they used their fingers, wrists, arms, rest of their body, etc. So, while NOT a physician, I AM somebody well qualified to diagnose pianistic technical problems - and If I saw one, that might be the FIRST thing addressed, or not. It all depends.
With some success in confirming a piano technique diagnosis in the 2nd step, the next would be to try something that differs from what IMO was causing the injury and test it out. If the pain returns/gets worse, we stop. And so forth.
And finally, as to "specific exercises", yes, there are PF "Holy 18" as some of us think about them - they absolutely work, but in a way, while on hand I'm glad they are becoming more widely known and easily enough purchased, kind of like and over the counter medication, and on the other I feel, that even though you can buy them over the counter, they are best used in a "by prescription only" setting working with a Feuchtwanger trained person who knows how to modify them, apply them, adjust them, and so forth.
Complicated? Yes, but last time I checked, so is playing the piano well without injury.