I had a very similar experience. I am a healthcare worker and had one of the first vaccines. However, I was also working up to 25 hour shifts during the peak of the pandemic. My rheumatologist isn’t sure if the vaccine or the extreme stress set off the PMR. I have done Olympic weightlifting and Crossfit for years and am 54 (dx approx 3 yes ago). I literally feel your pain. I am not familiar with the body I now have and it can be very discouraging. I definitely find support and encouragement on this site. Glad you’re here☺️