@betsyhase as was already suggesred it could be seronegative RA which can't be detected in the blood work. It often mimics PMR symptoms and can only really be tested for in a PET scan - where it shows as inflamed tissue inside the joints. PMR will show as inflamed tissues in the muscles and around the joints, not not inside. It is an important distinction because prednisone is not the best treatment for RA. Best of luck.