Which elimination diets have you used? They didn’t work?
The carnivore diet is often used in a elimination protocol because it’s very well tolerated by people. Red meat, water, and salt. 90 days - if that doesn’t resolve your issue then it may not be a food based issue.
Judy Cho has a book detailing the protcol and rationale - Carnivore Cure: The Ultimate Elimination Diet
In addition to eliminating all the organic toxins in foods which you might be intolerant of https://www.who.int/news-room/fact-sheets/detail/natural-toxins-in-food , it also removes industrial pesticides from your diet, which you might also be reacting too.
Hard boiled eggs, super food, very portable, easy to throw in a backpack or lunch box. Available in most convenience stores