Recently I felt like my symptoms had gone backwards dramatically. My gut was playing up at the same time. I weighed up the timings of everything and tried to work out which way the causation went.
In the end I reached a pretty clear conclusion: I'd been eating the wrong kind of peaches!
I'm FODMAP sensitive. I can't eat certain types of sugars. And the sugar content of different kinds of peaches is different (There's
a great app that spells out all the different FODMAPS and what they are in.) Fodmaps are sugars that gut bacteria love. Eating a lot of one kind can make certain species of gut bacteria mutliply a lot and emit a lot of gases (which is what farts are made of!).
I'd been picking peaches off a local tree. They were delicious! But after three or four days of a peach each day my symptoms had gone from very mild to definitely moderate. I have a lot of responsibilties at the moment and I was failing to meet any of them and what's more I was bitter and angry. I was lying on the couch, moaning ,feeling like I could barely stand. To be clear, while my guts were bad, that wasn't the overwhelming problem. It really was classic ME/CFS symptoms - fatigue, irritiability and cognitive fog.
I looked up peaches on the app. While yellow peaches contain only sorbitol, which I'm okay with, clingstone peaches contain mannitol. I know I should not eat mannitol. The stolen peaches were clingstone peaches. So I stopped eating the peaches and here I am 6 days later feeling much better. Back to mild. Back to being able to walk the dog, look after my spouse, etc.
The lesson is to pay very careful attention to what you eat. Slight differences like a change in brand of some product (or a different variety of peach!) can make a big difference. If you have not tried going fodmap free, it's time to try it. It's quite easy really. Fodmaps are deeply backed by science (the app in question comes from a major university). If you have questions about them please ask me.