Sore Tongue Pineapple Sore Tongue?

Sore tongue? - sore tongue pineapple

Recently, after eating certain foods (strawberries, oatmeal cookies with raisins, pineapple, almost all fruits) my tongue gets really sore. It came yesterday, when he ate a hot dog with ketchup and mustard on it. I looked online and said the thrush, herpes, heart problems, but I have nothing. I know for a fact. In going to my doctor at my next appointment (28 weeks of pregnancy to ask), but wanted an idea before. May I have food allergies develop? Cuz that food had never done before.