I read your story and yours is a lot like mine. I’m still playing the testing game but we all know I have an immune disorder but not sure which one. Sjogren's lung (pulmonary) disease would be one I would look into. The symptoms I have match the Sjogren's but I also have issues breathing still after three plus years. I will request a Rheumatologist referral. They ruled that out but I think that was still suggested to go see. I too have intense Disabilitating muscle and joint pain. Brain fog, and nerve pain all over. Getting treated for Fibromyalgia. Though there is more to it. My Dr is just treating symptoms. More tests being done. They have mentioned Cushings as well. Going to a Medical School Hospital and seeing the head Endocrinologist referred by my Cardiologist. I can barely walk now. Limited.