Hello Bob, I think on this subject you'll get plenty of replies!
i've had PMR since dec 2013. But prior to diagnosis I went through pretty much what the rest of PMR sufferer do, a general build up and increase of pain and stiffness to neck, shoulders, arms, hips and bum, knees, well I could go on and on. But about a week before my eventual rheumatologist appointment the pain and stiffness was at its most severe and at this time I also developed pain and tenderness around my whole rib cage on the rib just below my breast, the pain was worse just to the left of my sternum and I honestly thought I had something very wrong with my heart.
i had about a month prior to this been for a endoscopy and that revealed a sore in my stomach at the point were my osphogus (spelt wrong) meets my stomach.
like you when I was diagnosed I was prescribed preds and whilst still on 15mgs the pain in this area was still bothering me so I told my Dr and she prescribed omeprazole, believing that the sore in my stomach was being annoyed by the steriods, although I had the pain prior to steriods. Anyway, the pain cleared up nicely!
i been reducing my preds and got down to 9 mgs and I thought the pain was coming back again although very mildly, but following a flare up I again suffered from tenderness and pain around my rib cage, the one just under my left breast and to the left of my sternum. Even after upping my dose back up to 10 mgs the tenderness to my rib went away but this annoying pain remained. On Wednesday last week I went to my gp to speak with her about it. She gave me a full examination and blood tests but does not know what can be wrong with me, so she has booked me in for ultrasound told me to increase my omeprazole to 1 in morning and a further one in the evening. Tomorrow I go to see her to see for the blood results but funnily enough doubling my omeprazole has greatly improved the pain, but I'm still going to go for an ultrasound.
so to cut along story short, could you also have a problem with your stomach that perhaps a endoscopy rule out problems there.
it is also possible that PMR symtoms to include the rib cage and because this area of your body is effected by the PMR will react to (flare up) when preds are reduced although you say that the dose is still high.
these are just 2 possibilities, but I will say that the pain in this area was the most frightening as I believed it was my heart or heart valve.
before I went to the dr I looked up costochondritis thinking that my pain could be that. The Dr didn't say it was that but it could be I suppose.
Good luck Bob (it seems funny writing that name when not in connection with my husband)!
christina