Does overexertion cause PEM that makes things permanently worse?

Fatigue is not my biggest symtpom as of current its like swollen limbs and like inflammatikn, pins and needles as well as raynauds stuff and being rlly cold. But like i know a thing w lont covid is how if you exercise physically or mentally too hard it can cause PEM or setbacks. Im wondering if there is a general concensus if this is permanent or not. There are time periods where I feel like i could do a lot and vice versa. Its so hard to measure too. Any input would be greatly appreciated!!