Welcome @keetaboy, There are some conditions that mimic PMR. If it were me, I might want a referral from my doctor to a rheumatologist who knows more than a typical doctor about PMR and similar conditions. Here's an article on the topic that might shed some light...

-- Polymyalgia rheumatica with normal values of both erythrocyte sedimentation rate and C-reactive protein concentration at the time of diagnosis: a four-point guidance:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5911650/
I don't think I would grin and bear it if upping to 10 mgs didn't get rid of the pain but I would let the doctor know. Prednisone at the correct dose should alleviate the pain within hours not days (my non medical opinion from my own experience).

Have you talked with the doctor to let him know the 10 mg isn't cutting it?