It's either one of two things, a. An Upper Respiratory Infection, aka kitty cold,(NOT a Respiratory Tract Infection as Dragonchilde posted) or, b. Kitty Asthma/Allergies.

I have an 11 year old tortie, Mollie Rose, who has constant sneezing, wheezing, watery eyes and runny nose. The vet diagnosed her with kitty asthma and allergies. She's on an antihistamine for the cold symptoms and prednisone (only as needed) for her asthma.

I think a trip to the vet is in order. Let us know how you make out!