I adopted an American Curl who had a chronic sneezing problem. I thought it just might be from the dust in the kitty box. I finally had her vet checked because the problem didn't get any better, plus I got tired of being sneezed at in my face while I'm asleep. Anyway, my vet put her on Clavamox and it didn't do anything. So he put her on Zythromax, a new antibiotic liquid. She was on it for quite some time, till it was gone. Her sneezing stopped. Then I took her to be spayed and the sneezing came back again. Back on the Zythromax she went. She has since finished it and has had no sneezing bouts. The vet said it could very well be herpes related and is brought on by stress. I keep a bottle of Zythromax around all the time just in case. He did tell me that when she has an outbreak of sneezing again to isolate her as it can be passed on to my other 6 cats. But so far, so good. I'm keeping my fingers crossed.
I would definitely have her checked out just to make sure, though. It'll give you piece of mind. Cats can and do have allergies. Symptoms of uppper respiratory infection are sneezing, runny nose, watery eyes, congestion in the chest and lack of appetite.