i had a kaplan question on it, this is what i took from it....
Fibromyalgia - widespread musculoskeletal pain that improves with exercise, fatigue, headaches, painful trigger points upon palpation of the trapezius and lateral epicondyle of the elbow (buzzwords), no signs of inflammation, normal lab values. Patients seem to respond well to TCAs, specifically look for amitryptiline. If that is not option, skeletal muscle relaxants with strong anticholinergic properties are also used.