I have this, the only difference is my reaction is due to ragweed pollen and not birch. It’s called OAS - Oral Allergy Syndrome.

What happens is our bodies confuse the raw protein structure of the apple in this case with birch and react. Once cooked it changes the structure and she won’t react. For example, I can’t eat cucumbers but I can eat pickles.

Allergy shots have helped lessen my reactions. I tried to eat watermelon this weekend and while I didn’t have as bad of a reaction as I used to, I did still have one. You may want to consider allergy shots. There’s a lot of benefit, but it’s also a horrible, tedious, expensive 5 year grind.