You can try this and try that ad infinitum, and almost everything will seem to help some or help for a while, as optimism kicks in. Go see a medical doctor. Whether it's a GP or specialist is up to you. If you have bad luck and the first one is a dud, try another. The issue may be something you don't expect at all.

After that, think about this. I met a man once who was noted for his fast, talky guitar style. He told me he could do it because he had had a luthier replace his frets with extra-large frets which enabled his hands to fly over the fretboard, exerting minimum pressure. This might be worth a try because it would take less effort to play.