Looking for Information on Poly Myalgia Rheumatica

My doctor thinks I may have it too. I have been in so much pain lately (months) and fatigued and just general malaise and he thought having CoVid in Sept may have spun my system into a huge flare up so he put me on Prednisone. Well I had THE BEST response to it and the best two weeks of my life in these past twelve years. So when I went for a recheck he said he thinks I may have PMR because one major sign is great response to steroids and it is also the only treatment. But he still took me off them and started me on Sulfasalazine to see if it works for me. I guess it’s also going to help determine whether I have PMR or not. So I’ve been off the Prednisone a few days now and the pain is reappearing. Another odd symptom I had horribly was shortness of breath. Not sure why. He did do a Transferrin Iron test and it showed low iron saturation so I’m in iron tablets every other day. That could be a cause if the shortness of breath but after I started the Prednisone that also went away. I’m talking months upon months (a couple years actually) of this symptom. Gone just like that. So I can only assume I had inflammation in my lungs or something else was inflamed and pushing into them? Well either way it’s slowly creeping back up on me along with the pain. So I’ll continue the new drug a while and see if it doesn’t anything. If not then he’s gonna dx me with PMR and put me back on Prednisone. I just do not want the side effects of it; especially weight gain. Already gained 80lbs in ten years. Trying to lose it now! Anyway, I have never heard of the condition so trying to learn a little about it.