How was fibromyalgia discovered?

Wise physicians. It was identified by experienced wise physicians who realized that this was not due to inflammatory changes. It was put together in view of the symptom complex and the findings and compounded by poor exercise, poor sleep and /or poor control of psychologic issues. Your government has cheapened the value of wise physicians and this will backfire with time. We need wise physicians!
It Wasn't. World concensus is that cause is unknown. Criteria for creating the symptom constellation, as a quasi-diagnosis, was a duty undertaken by a committee of rheumatologists in early 1990's. Fibromyalgia diagnostics not done by tests or studies, but by committeee vote; probably to deal with hordes of "histrionic women with exaggerated pain", for which unique billing codes were needed, in the 1990's.