I personally am critical of going up or down on prednisone dosage. I was diagnosed with PMR about 4 years ago and have had bouts of low and high doses in the intervening years with very little impact. I dreaded having to be on steroids for a long period with all their scary side affects!
I am now off prednisone for three months due, I think, to perseverance and scepticism that I really had PMR. I now and then get the symptoms similar to those of PMR but am not convinced I have it!! It was around the time just before I stopped taking prednisone that I was diagnosed with prostate cancer (low level fortunately) and am receiving radiation therapy.
Interestingly my GP felt the concentration on the cancer would likely remove the PMR symptoms or at least reduce them significantly caused, I guess, of my brain focusing on the cancer! This is precisely what occurred - one wonders!!
I do get some neck and lower back aches but since starting some neck and back exercises I got from a visit to a Physiotherapist the aches have greatly reduced almost to the stage where I don’t notice having aches at all!
I therefore question the symptoms allegedly due to PMR and I believe perhaps you might consider seeking advice other than from a Rheumatologist. This, I stress, is not to lose complete faith in a Rheumatologist but feel that PMR is too readily blamed for the symptoms you undoubtedly suffer as I did for four years or more.
I wish you luck in your journey.