So my 4 year old was recently diagnosed with food allergies after having an upper respiratory infection

It’s been getting progressively worse in the sense she’ll just eat a small amount of an allergen & she still will develop stomach pains, vomiting & sometimes diarrhea the next day

Is there any way I can prevent her from experiencing any stomach pains/vomiting besides obviously avoiding the food? Or if not what can I do to soothe the process so it’s not as severe?

Like her allergy test showed she wasn’t allergic to sesame seeds, yet she had some bread with probably like 4 sesame seeds total then the next day had the stomach pains/vomiting (I’m assuming it was the sesame cause that’s the only new food she ate that day)

I would just love some tips; so far I’ve done peppermint tea & a warm bath when she’s actually experiencing the symptoms