Psoriatic arthritis is a seronegative inflammatory disease. It is more likely if you have or ever had psoriasis. Do you have psoriasis?

I was diagnosed with reactive arthritis at the age of 32. Reactive arthritis is another type of seronegative inflammatory disease similar to psoriatic arthritis. For me, PMR was diagnosed at the age of 52. The very first question I asked my rheumatologist was, "What happened to reactive arthritis?" My rheumtologist simply said it was unfortunate but I still had reactive arthritis along with PMR.

As hard as it was to comprehend, I gradually accepted I had both PMR and reactive arthritis. Unfortunately, reactive arthritis was overlooked until I was treated with a biologic that targeted the IL-6 cytokine implicated in PMR. As soon as I tapered off prednisone, Reactive arthritis and uveitis flared up again.

You might want to suggest that your IL-6 level be checked although that rarely happens.
https://www.hmpgloballearningnetwork.com/site/frmc/literature-review/comparing-effectiveness-il-6-inhibitors-and-glucocorticoids-treating#:~:text=IL%2D6%20has%20been%20implicated,the%20IL%2D6%20pathway%20effectively.
Targeting the correct inflammation pathway seems more important than the diagnosis. Unfortunately, your diagnosis largely determines your treatment.

Prednisone will help almost any type in inflammatory pain and isn't exclusively used for PMR. Most rheumatologists will want to avoid long term prednisone use so they seem reluctant to diagnose PMR especially when you are younger.