Many times, "allergies" are due to what is in their food. In Zanders first year I switched him to Natures variety he started having reverse sneezing, very often. My vet was ready to medicate, I told him let me research this and I will get back to you. After doing some research I changed his food to another, it stopped. No meds so far, Zander is 3 yrs. old.
Something to think about. Good luck.