From my own research and observations I'm quite confident it is, as you elude to, an auto-immune related disease. The two major triggers for me are exercise; particularly anaerobic e.g weightlifting, and alcohol. Alcohol actually alleviates the symptoms for a day or more and then undoubtedly i'll struggle for a few days after that. Which points to alcohol's suppressive effects on the immune system.
I really really hope this, and similar research[1], turns into something tangible
[1] https://med.stanford.edu/news/all-news/2019/04/biomarker-for...