It wasn't anyone's fault. Everything was tried that could have been tried. There were additional problems but PMR was my "primary diagnosis."

Your doctor sounds very wise to me. Splitting my dose helped my early morning pain. I would wake up at 3 a.m. every morning in extreme pain. When I split my dose and took 2/3 of my total dose at 8 a.m. and 1/3 of my total dose in the evening at 8 p.m. that allowed me to sleep all night without pain. My total daily dose was actually less when I split my dose. I was able to sleep all night without pain and being able to do that was a blessing.

I wasn't a fan of pill cutting either. I had pills in every denomination available: 20 mg -- 10 mg --- 5 mg --- 2.5 mg --- 1 mg tablets were all ordered for me when I needed them.
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=63e2d3c7-8120-401b-a826-c98754797026#:~:text=PredniSONE%20Tablets%20are%20available%20in,10%20mg%20and%2020%20mg.
You can see that Prednisone is used for many things. I had multiple autoimmune disorders so that complicated things. I had inflammatory arthritis and PMR. It is good that your doctor is looking for other things. PMR responds to prednisone but that doesn't confirm a diagnosis of PMR.

A diagnosis of PMR doesn't mean you can't have something else come along with PMR.

"Having one autoimmune disorder increases the risk of having more than one."
https://pmc.ncbi.nlm.nih.gov/articles/PMC3150011/#:~:text=Multiple%20autoimmune%20syndrome%20is%20a,%E2%9D%91