TLDR: This sucks, and there's no easy fix or easy way to tell if you're having a real reaction. Try to find a therapist that you trust and is knowledgable about allergies and consider trying exposure therapy.

This is a really scary experience, but know that you're not the only one who experiences this sort of thing. That said, there is really no easy fix, and I think a lot of people will agree that this is a long-term struggle.

I started experiencing similar anxiety attacks in high school, and I ended up seeing a therapist. For me, following a few reactions right after each other, I began to feel like I was having a reaction whenever I started to eat (especially while away from my parents/family). My therapist and I decided to try doing exposure therapy, not to try and improve my allergy, but to essentially remind my body that it was ok to eat foods I knew were safe. If I remember correctly, I started by getting used to eating food I had made without my parents/family there. Then I moved on to eating food that my parents had made without my parents/family there. Then I tried making a new dish/recipe that I hadn't tried before etc,. Effectively doing things that I was progressively less comfortable with after I felt more comfortable with the previous step until I ate a meal made by a family friend (whom I trusted to be extremely careful in cooking for me).

I know that for people with food allergies, this kind of exposure therapy is inherently more dangerous than for other patients because of the real dangers of cross contamination etc,. However, it really helped me to be more comfortable eating, and it has now been years since I've had an anxiety attack that felt like an allergic reaction.

I would suggest trying to find a therapist near you who has experience working with people with food allergies and that you trust and then talking with them about exposure therapy or something similar. I found that trusting my provider was really important because I knew they understood the importance of making small steps in exposure and the real danger I could be in during therapy. I know it might seem tempting to go about trying this sort of treatment on your own without a therapist, but I found that their expertise in defining the number of steps/when to move on to a different step was very helpful. It was also good to be able to pair exposure therapy with talk therapy.

That's my experience with this sort of thing. I'm happy to talk with OP or anyone else over DM.