I’m so sorry to hear of your struggles, but I don’t think you are alone. I have a couple of thoughts… Zantac is not good to take long term, but there are few issues with Zyrtec. Maybe worth a try? Parasym Plus is ENCOURAGED if you are on antihistamines, to help off-set some anticholinergic effects. They don’t counteract each other because the purpose of antihistamines is to decrease histamine, not to decrease acetylcholine. The anticholinergic effects of antihistamines are SIDE EFFECTS — not their purpose. Does that make sense? Finally, I’m not sure if you saw this in the book, but unless your tryptase is high, there is a decent chance that mast cells are not the major underlying problem for you. We need to keep our minds open to all aspects of inflammation, including the role of all histamine-producing cells, or risk continuing illness.