Variance is a big deal with this game. As it is with games involving few trials, and subtle differences between good and bad results. It’s also really tough to diagnose from the right perspective, when it’s happening to you.
I.e.: Do I suck now? Or have I been playing as well or even bettet than before, but I’ve just been unlucky?
Good Strokes Gained data should help answer the question, but even so, unless we’re playing a lot, and have a nice big dataset to work with, it’s still tough to reject that null hypothesis.
OP, if you haven’t read The Four Foundations of Golf yet, take it for a spin from your local library. Or buy a copy. Adjusting your expectations as a golfer, to what’s realistic, to what’s actually happening, is a big part of that book, IMHO. It’s really useful.
If you’re not having fun, I’d stop doing it. But maybe changing your feelings about the game instead, can bring the fun back.