The return of your pain being described as a sledgehammer is very familiar. I ended
up in so much pain and thought the fibro had simply gotten worse. Then ot got so bad that upon waking up, I couldn't get out of bed or walk without assistance. I went to the ER and they were baffled. I saw my general doctor a couple days later and I was diagnosed with Polymyalgia Rheumatica (PMR). It is rare to have both fibro and PMR but definitely possible.
Perhaps ask if you could get bloodwork done to check for it. There is more information on the PMR Board and sone very friendly and helpful people. It's worth a try because although there are side effects to prednisone, the best is being almost pain-free. Sadly it doesn't help with fibro pain, just the inflammation caused by PMR.
Good luck.