Hello after an illness (upper respiratory) I developed an autoimmune disease for which I am seronegative. I went to Mayo and was dx with sjogrens. I had a neuro-presentation first (no dryness...dryness came about 1-1.5 yr into the disease). So Mayo did lots of testing and biopsies which were positive for my disease. Local guys just relied on blood work:( So Mayo was a very important visit for me as I finally found out what was wrong with me. ME/CFS, sleep apnea, autoimmune diseases may be something to look into. Good luck!