Well, pizza is 9 times out of ten full of preservatives( pepperoni and other deli meats are not good choices for anyone, but especially food sensitive folks) has MSG which is a know trigger of symptoms and is likely in the pizza, or dairy, or gluten, or tomato(on the no list for histamine) Fast foods, and prepared foods are tricky to pinpoint what exactly you are reacting to… they use lots of chemicals in the processing, preservatives, and hidden allergies everywhere 🙂
Maybe if you “take a part ” a pizza and trial each part? Eat some just pepperoni and give it a couple hours- if symptom free move on to the tomato- if symptom free move on to the crust.. etc.
It is tough to give up foods that give us comfort, and that we are accustomed to- but, Abby has done gobs better when we figure out and remove the culprit item..
Hang in there and hope you feel better soon,