In this video from Mayo Clinic radio, you can hear from Dr. Arya Mohabbat, the practice chair of Mayo Clinic's Fibromyalgia and Chronic Fatigue Clinic about a disorder called fibromyalgia. It causes pain and discomfort all over the body, as well as other symptoms like changes in mood and memory alterations. It has been suggested that in the disease, the brain is amplifying pain signals from the body.
It had once been suggested that this disorder was all in the mind of the patient. But, it's important to acknowledge that humans have had a lot of nutty ideas at one time or another. It is now accepted that this is a real and verifiable disease, a "chronic, centralized pain sensitivity syndrome," as described, and explained further, in the video.
This condition is set apart from inflammatory conditions like lupus or arthritis, although it can share features of some of those diseases. Defined diagnostic criteria have been set (and are mentioned in the video), and there are treatment options for those that suffer from fibromyalgia. Researchers are working to learn more about what is causing the disease.