I' m not sure what a flareup of FM means.  Sunday I had such severe pains in my back and up to my left shoulder that I could hardly breathe.  I have never experienced such severe pain before.  I would describe my normal pain with FM as more of an ache than a crippling pain.  My son insisted that I go to the hospital eventhough I could hardly stand.  They gave me morphine for the pain .  This gave my immediate relief but soon wore off.  I don't know how I could stand this kind of pain again.  Is this what is meant by a flareup?  Thank you for your feedback.