explosive dhiarroea, resulting in a sore anus
Better a sore anus from diarrhea than something else...
Am I doomed?
No. I hate onions and never had an issue finding food in Poland without it
Any suggested restaurants that cater to intolerances and alergies?Will people understand the issue easily?
People will understand. One of my cousins is vegetarian so he always asks about the meat content in things like sauces for example. They've always been accommodating, except for once when they served him a bowl of chicken noodle soup. I doubt you'll have issues. I'd mainly stick to restaurants that are located within the rynek since as a rule of thumb they tend to be very good. They also deal with a lot of foreigners so they're use to accommodating all sorts of people.
I'd avoid pierogi are often fried alongside onions and/or onions are served as a garnish.