I agree that Covid vaccinations can trigger PMR, but are you sure that is what you have? I think that most people experience immediate relief when put on Prednisone, unless your dose was too low to begin with. Just guessing . I have a very mild case that only hurts in bed and now it is confined to my upper shoulders. Currently taking 2 mg. Good luck!

Age 72 .I too was healthy walking 3-4 km daily (nordic walking). A week after the 1st Covid vaccine Booster i developed weakness of my joints and ligaments , couldn’t stand , roll over in the bed, attend to personal hygiene . My family Doctor didn’t have an answer for the shocking suddenness of the attack on my body . I suggested to her I had PMR caused by the vaccine (having done searches on medical Web Sites.) Prednisolone 20 mg was prescribed over a year ago , now on 5 mg daily , about to taper again in a weeks time for the 3rd time. I saw a Rheumatologist early on he diagnosed PMR vaccine related. Having excluded Arthritis and other causes he prescribed Methotrexate once a week for 4 weeks combined with the Prednisolone. I do Qigong exercises daily for 15 minutes x2 daily and find them extremely helpful especially for my neck shoulders and arms and balance (.Master Change Lee (Spring Forest Qigong) youtube is probably the best and most authentic teacher of Qigong on youtube. The exercises can be done by anybody and very effective. I’ve just started taking Flexofytol Forte capsules (a mixture of Curcumine , Boswellia Serrata and Vit.D) produced by TILMAN - Pharma a herbal- based Pharmaceutical Laboratory in Belgium. It has been tested on about 1000 patients by their family Doctors in Belgium with good success for (Arthritis - Symptoms. But one must consult one’s doctor first . I’m hoping to avoid another relapse as the side effects of the strong medications like Prednisolone Methotrexate etc are somewhat concerning. However,! it’s important to have good quality of life .and be reasonably pain free and never give up. The vaccine save billions of lives but why some of us react so badly we may never know. I certainly did not have the 2nd or 3rd boosters and nobody could persuade me to.