Yeah, now that there is a confirmed link between microbiome and CFS, this could be a plausible explanation. ie if your ME was being caused by some bad bugs, then they might have got flushed out in the back (and front), but then made a comeback as many may have survived in the gut biofilm. I just ate some chicken that was a bit past its optimum, so im hoping maybe i get food poisoning and see what the result is.Does make you wonder if suggestions of gut bacteria being implicated in ME could be on the right track. When really ill it can purge the system pretty thoroughly. Maybe the body just gets a brief respite from bad bacteria (or good bacteria in the wrong part of the gut?), and/or toxins produced by them? Sarah Myhill discusses gut bacteria issues quite a lot.