It takes time to find your trigger foods, but it's easy to do and doesn't cost anything.
Just keep a food log - a journal where you write down the date, time, what you eat and drink, medicines, and your reactions, especially in an hour or two.
Once you get a list of foods, hamburgers, pizza, waffles, or whatever, you have to break down the ingredients and do "challenge testing." Bread - find a small plain pita with no additives. Not all that easy to do. Cut a slice that would fill a tablespoon and eat it. If you have a reaction stop! If not, after 20 minutes, eat two slices, wait 20 minutes more, then 4 slices, then 8 and finish with 16. Do the same for each part of every meal that gave you a reaction.
This will take 2-3 months to finish!!!
When you get your refined list, google each item on the net with "food alleriy" or "food intolerance."
My list was fairly strange: maple syrup, gelatin, store bread, anything with powdered sugar or corn starch, ...
I came up with sulfite intolerance. I don't get the allergic reaction a few people do, just reflux often followed by racing heart, which is serious.