@keelin - If the prednisone is not providing pain relief, then maybe you don't really have PMR but a condition that mimics PMR? I know you've mentioned you've seen 2 rheumatologists in other posts earlier but if it were me I would try to ask a bunch of "why is the pain not being addressed by the treatment" questions and maybe seek help at a teaching hospital or major health facility like Mayo Clinic. I'm sure there is a treatment out there somewhere that can help.

-- Diseases that mimic polymyalgia rheumatica (PMR):
https://www.medicalnewstoday.com/articles/diseases-that-mimic-polymyalgia-rheumatica
-- Clinical manifestations and diagnosis of polymyalgia rheumatica:
https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-polymyalgia-rheumatica/print