Your experience seems to mirror mine--got PMR after my 2nd COVID vaccination. No rise in inflammatory markers, so took 4 months to diagnose. I guess I just had a mild case because I only hurt while laying in bed! I was off 10 mg. of prednisone within about a year. BTW, I also eat a whole foods, organic diet, high in antiinflammatory foods. This may have helped me a lot.