Reddit mentions of Never Bet Against Occam: Mast Cell Activation Disease and the Modern Epidemics of Chronic Illness and Medical Complexity

I would recommend it. You'll have to be stricter initially and maybe for years but then you should be able to have more stuff. Allergy specialist might not be much help with the MCAS either. But hopefully they will.

I recommend this author and this book is quite useful, if somewhat old. I accidentally stumbled on the histamine intolerance diet in this book - because I was basically already on the diet, just needed to eliminate tomatoes and vinegar. (Which is a nightmare initially but you'll feel better.)
Dealing with Food Allergies: A Practical Guide to Detecting Culprit Foods and Eating a Healthy, Enjoyable Diet There's a newer version "packaged" as a text book for nutritionists. I just bought it used but it's more expensive.

You're going to need to figure out what your body agrees with. Histamine is a bucket to fill. You don't want to overflow the bucket. I'd start by dropping alcohol, tomato, food with preservatives, 90% soda, and vinegar.

You also want to learn about the age of food and how histamine develops as food gets older. You probably don't want to eat cooked food that's older than 2-3 days, assuming it was stored properly. You might not want to go over 48 hours. (Some people will eat leftovers a month later and then don't understand when they get sick. Hopefully this doesn't describe you.)

Be careful of all the websites and recipes and, well, shit, out there. There's so much more now than a few years ago. When you Google histamine intolerance now there's even more to wade through. Joneja has a website and other books. She's a fantastic source.

A more in depth book about MCAS by Afrin came out last year.

THIS is a fantastic academic journal article about histamine. I've seen it cited multiple times. It has a few tables/graphs that are super interesting.

Remember, your first and best sources are doctors and people with licenses. People who are sharing their experiences are great too but they might be very wrong and who knows how your body is different from theirs. You have to learn to understand what your body says is good or bad and some days that varies.

oh! almost forget. You might want to avoid NSAIDs if you don't already. Depends, on you, of course.

edit: I am not actually "officially" diagnosed but I clearly have fucked up mast cells and a fucked up immune system.