I notice that a couple of people have mentioned burping: is this something that's common with ME? My caree gets it when she's particularly exhausted, and it has a noticeable smell. Very odd.
I get it because of acid reflux, often without heartburn pain or any other indication of reflux. It's probably quite common in people both with and without ME.
I use burping to decide if I've had enough sodium. If I burp in 3 minutes or less after taking some sodium bicarbonate, I assume that I have. If not, I keep taking more until I burp in 3 minutes or less. I don't know how reliable it is, but it seems to stop me getting hyponatraemia (low blood sodium). Maybe the person has a shortage of something?
She actually said today that it's when her whole upper body, especially the head, tenses up, and the insides with it.