I put my malaise down to having too aggressive a style coupled with insufficient amplification, trying to be too clever, and band-practising with those damaging traits 3 times a week.
I'm getting back into playing now (wouldn't be on this forum else), but instead of attempting to be the greatest guitarist in the world I'm settling for attempting to be an adequate guitarist entertaining himself oo er occasionally and quietly in the house. Not a story on which Hollywood blockbusters are based.
My advice is stop when it hurts, have rest days from practice, and exhaust every route you can in the search for prevention or cure.
Oz.