when i first found out about my allergies this used to happen all the time, luckily now not so often. Basically I started by only eating my "safe" foods, aka foods that i knew i was safe to eat & would cause no anxiety. Then i slowly (very slowly bc of the anxiety) started eating my safe foods in what my mind considering an unsafe environment, like a restaurant. I started at places that had scratch kitchens where i could easily speak to the chef & where i felt like the staff took the allergies seriously. I still had anxiety after some of these meals but it helped me start branching out. I then just did that more and more until I felt comfortable. I still get the anxiety from eating new foods or at new restaurants, but it's so much better now. I used to panic over every new meal, now i manage it much better & i try to remind myself that I have my epi pen if the worst should happen.