vegan

First, I know medical care is expensive in the USA, but I'd really recommend getting tested if it's so serious that it's putting you in the hospital. Vegan or not, you might eat something that kills you down the line. Debt is better than death.

Second, I think you'd be surprised by how many allergy friendly processed foods are also vegan. Both groups are such a tiny part of the overall population that often times they'll just group us all together and assume every vegan is allergic to something. Some of the more common allergens that affect vegans are soy, wheat, sesame seeds, and nuts. I've seen various premade pizzas, proteins, crackers, and cheeses avoid some of these allergens. I'd say out of the most common ones, soy is probably the hardest to avoid. However, if you're eating out, especially at a vegan place, I've never had issues finding out if something had an allergen or not. In fact, sometimes they'll advertise it right in the dish description.

Of course, there are food allergens out there you'd also be avoiding by going vegan like dairy (I didn't realize I was allergic to it until I stopped eating it), eggs, meat, and fish (shellfish is a major one). Out of the most common allergies, it's about a 50/50 on whether it affects vegans or not. I will say, as a vegan in America, I've gotten way less food poisoning since I went vegan. I basically just need to be careful about washed greens and restaurant cleanliness nowadays, so that's been nice.

Again, I'd really recommend getting tested if you can, so you know what exactly it is you need to avoid. Tell your doctor about your family history. If you're American I can recommend a specific grocery chain that likes to focus on allergy specific vegan foods, but I can tell you now that it won't be cheap. Once you know what affects you, you're better off cooking at home.