Ha, totally with the treatment fatigue! I'm just mentally done visiting more doctors who are more often than not clueless and a waste of my time. Not that I know everything about
my condition, but most times I have to ceaselessly fight to get them to acknowledge the fundamental basics I'm dealing with, not to mention my treatment decisions which most would view as beyond insane. That said, I would think most doctors who are experienced with MCAS will have some knowledge of lyme/coinfections/mold/metals/etc since these can be important factors contributing to the condition.
My llmd is great and has helped me a lot, but I still have had to do a lot of trouble-shooting on my own. These are complex conditions, no doctor has all the answers which is why I believe we have to self-educate as much as possible so we can understand our options and potential strategies.
For my diet, I didn't go for low-histamine, but I basically went with a vanilla approach of cutting out refined sugars, processed foods, minimizing dairy/gluten. I found the first two most helpful. Astroman and Dude Abides are great resources when it comes to diet and tailoring the approach to the individual. I think astroman recommends certain tests, including food allergy test. I also found exercise would greatly exacerbate my symptoms, and I remember reading somewhere that it can trigger histamine release... I've wondered about
that dynamic. But the exercise intolerance has improved a ton as I've treated the infections (most especially babesia).
I take antihistamine combos of allegra and zyrtec, and am also taking quercetin. Like jb1994 mentiosn vit c can help as well. Aerose91 posted some herbal mast cell stabilizers but I can't recall the names. I used the following article as a bit of a jumping off point of things to try for MCAS. Maybe could experiment with diet first, then explore other options? There is also a facebook mast cell group which I found helpful.
https://www.lymedisease.org/lyme-sci-mcas-agony/