The chronic disorder of unknown cause characterized by tender points and fatigue?

The answer is fibromyalgia.

Fibromyalgia is a chronic disorder that causes widespread pain and tenderness in the body, as well as fatigue, sleep problems, memory loss, and mood disturbances. The exact cause of fibromyalgia is unknown, but it is thought to be related to abnormal levels of certain chemicals in the brain and spinal cord that control pain and sleep.