pet or seasonal allergies

My husband's cat has been with us since about last Nov. I didn't "notice" really any symptoms. lately, for quite some time, I have bad nasal congestion along with here and there sneezing. I can't breath out of my nose much. I'm super sad cuz I love his cat, but don't want not be able to breath. what can cause all this congestion? can it be something else? will it reside on its own?