Wow. I just read this:
“Intriguingly neuropeptide Y – a proposed biomarker in chronic fatigue syndrome – can induce mast cell degranulation and a subsequent lowering of blood pressure. Biaggioni found that POTS (postural tachycardia syndrome) patients with mast cell activation experienced episodes of flushing, shortness of breath, headache, lightheadedness, excessive urination, and gastrointestinal symptoms such as diarrhea, nausea, and vomiting. These symptoms could be set off by such normally innocuous things as standing for long periods, exercise, premenstrual cycle, meals, and sexual
intercourse”
From
https://phoenixrising.me/myalgic-encephalomyelitis-chronic-fatigue-syndrome/fibromyalgia-trial-shows-promise-for-chronic-fatigue-syndrome-mast-cells-and-ketiotifen-in-fm-and-mecfs/