@ChrisD Your ME follows similar lines to me. For me it went Chlamydia - Fibromyalgia - Flu- ME. I think unbeknownst to me the reactive arthritis was there from the start. I doubt very much that I would have ME now if I had not contracted Chlamydia when I was 20 years old.
That Chlamydia infection changed me. It was a rebound too. I was given an antibiotic pessary tablet vaginally and I reacted badly to it, damaging the microbiota. I never returned to a normal microbiome. As you could imagine I had problems convincing doctors something was different, they began to see me as having psychological problems. I was young and it was the 80's.
Like you, I didn't know of the Chlamydia connection to reactive arthritis. None of my doctors clicked either.
It wasn't until I came here to PR that I learned of reactive arthritis , 30 years on.
From what I have read, a flu can flare up reactive arthritis. Looking back at my severe ME onset. I now wonder if 'some' of that was reactive arthritis along with ME. I definitely had a nasty flu but I remember at the time having a reactive arthritis symptom on the soles of my feet and that is blennorrhagica. I had a 3 on one foot and 4 on the other. I also had painful knees. But I had a ton of other severe symptoms at severe, one of which I think was meningitis.
Only if you don't mind, have you tried any treatments for reactive arthritis? Any help?