I have various strange allergies to things such as celery, carrots, apples, what to do?

Eliminate from diet: People with pollen allergy also have mouth itching from eating fresh celery, carrots and apples. This is due to the similar protein in the pollen. Typically birch pollen and apples are connected; weeds (like sage brush) is linked to celery and carrots. If the only symptoms are mild mouth itching (no GI or breathing issues), these foods when cooked at high temps can be tolerated. See allergist.