My daughter seems to have a ketchup allergy? Ever heard of that?

Corn, tomato in it. I have seen people react to ketchup because they had a tomato reaction or because they had a corn allergy. For the corn allergy, there are now ketchups available free of high fructose corn syrup, and I have seen eating those help. If tomato is the problem, a different flavoring will have to be selected. Other ingredients can also cause the problem.You can figure out which one by testing if lucky.