A doctor familiar with fibromyalgia, however, can make a diagnosis based on two criteria established by the American College of Rheumatology or ACR: A history of widespread pain lasting more than 3 months and the presence of tender points. Pain is considered to be widespread when it affects all four quadrants of the body; that is, you must have pain in both your right and left sides as well as above and below the waist to be diagnosed with fibromyalgia.