I'm a little worried about my chubby feline. I noticed last Friday that he sneezes a lot more than the usual. He can sneeze 5, even 10 times in a row and then not sneeze at all for hours. I don't see anything coming out of his nose, by the way. He seems perfectly happy and eats normally as well.
I'm wondering if he could be allergic to something, but what? I didn't change his diet or anything. Could it be the pollen? I've been sneezing like crazy for the last few weeks, perhaps he is allergic too

. I can't see how it could be rhinotracheitis: he is a only cat, stays indoors and is up to date on all his shots. And until yesterday, I hadn't been at the shelter for 3 weeks. What could it be?
Any opinions would be welcome. I'll make an appointment with the vet if I must, but I just spent almost 200$ last week for what I thought was ringworm - having a vet come over for another false alarm would really make a big hole in my budget and stress him needlessly. Thanks in advance!