Tips:
Elimination diet and slowly add one at a time a small portion of suspect food and wait a day or two be fore you try a different food.
Keep a food diary (date, foods consumed and when + how you feel, reaction or not over time). Sometimes reactions occur within a few minutes and some show up or are felt the next day.
When you find what you react to, look up the different names for that type of food.
Watch out for what you react to in medicine (the medication it self as well as the inert ingredients).

My daughter was given a diet with no nuts, no fish, no sea food, now sweets - at all!, only freshly cooked food, no longer than a day in fridge, no cheese - only mozzarella cheese in whey liquid, no fermented food.
And, of course, without the odd things that she is allergic at: potatoes, apples, sour cherry, peaches.
In a year the next allergy test didn't show any food allergy.
About the respiratory allergies: head shower and changing the pillow cases like every day.
Hope it helps.

Avoid food that cause allergies.

I find having safe fermented foods really helps with reducing reactions-things like kimchi, pickles, kefir etc. I make a lot off my own safe foods at home (I’m allergic to many common food preservatives)…

Eating clean has truly been my saving grace. Eliminating foods with colorants, preservatives, additives, hormones etc. that led to allergic reactions.