One doc said fibromyalgia is a diagnosis when everything else has been ruled out. He mentioned sarcoid disease. Any other diseases I could check out?

Yes. A basic lab panel to rule out endocrine or autoimmune diseases might include blood counts, blood chemistries, thyroid function, liver function, vitamin d, esr/crp. With risk factors imwould consider hepatitis panel, hiv.
JHS. Joint hypermobility syndrome is certainly a disorder to be ruled out. This genetic disorder with female prominence is highly associated with development of #fibromyalgia. A doctor familiar with brighton criteria (1998) should be sought out. Physical therapy follows biomechanical analysis and blood tests to rule out autoimmune, viral, and endocrine disorders causal of problems not fibromyalgia.