I have had the same problem for many years. Been through so many tests over 9 years. Now esophagus is not working properly, have Hashimoto's but my thyroid is still kicking. Finally had blood work done that shows I have Connective tissue disease with overlap. So far, it's Scleroderma, Lupus, Raynaud's, and a few more. Possibly have them do bloodwork for autoimmune problems. Stick to your guns with the doctors. Sometimes it takes years to figure these out. Big hugs.