Are you being seen by a rheumatologist? FM is common with autoimmune diseases like RA. I know you tested negative, but a good rheum may watch you to see if you develop into a disease. I have UCTD and that’s kind of how it was for me. I had a lot of weird symptoms and nobody knew what was going on and the rheums just watched me and eventually I showed more symptoms. You could also be something called “seronegative” which means you have something but your blood work isn’t showing it.

Oh one thing I've been telling fibro people that suffer with IBS GERD low appetite weight gain of weight lause severe nausea is to get checked for gastroparesis because I have gastroparesis I just found out last November. I suspect that there are A LOT of firbomyalgia people with delayed stomach emptying or gastroparesis. Swallowing issues are also a symptom. There are varying levels of functionality but it's basically caused by nerve damage to the vagus nerve. Diabetes is a common cause but I have talked to a lot of GP warriors that have ideopathic Gastroparesis and I polled people in groups and found many have also been diagnosed with fibro.