I'm sorry about the setback and that you haven't found a good treatment.
I think that an immunological treatment might help although you don't have a specific autoimmune diagnosis.

I had once a positive borderline ANA results, and my CRP has always been negative (except when I had Lymphoma). But immunological treatment (Rituximab) is really helping me now with the POTS and SFN, so there is no doubt it is caused by some kind of autoimmune disorder.

It took me many years to find a doctor who was ready to listen to me, see the whole picture and not just look at the blood results. He agreed that based on my medical history to try immunological treatments.