Excessive sneezing.

About 4 or 5 days ago I noticed my cat started sneezing alot out of the blue. She has been sneezing constantly the past few days and I'm not sure why. I also noticed that alot of the times she sneezes she seems to have difficulty at first... she makes a few short half sneeze like sounds and has a look on her face like she's having trouble getting it out then she'll have a full blown sneeze shortly after. She's never done this before so I don't think it's allergies but I have no idea. She seems to be acting normal like she always does except for the sneezing. There is no blood in her snot. Whenever I've seen it, it looks clear. Can anyone give me some advice as to why or what is causing this ? Thank you.

Does she go outside? It could be several things. The most likely are a virus (like feline herpes) or a foreign body, since it started suddenly. Is the discharge/snot coming from one side or both nostrils?

We have a screened in patio she goes out on to relax and play. That is where her potty box is aswell. I also have 3 other cats and none of them are having her symptoms. I can't recall if the snot came from one or both nostrils. I'm pretty sure it was snot that came from her nose. It didnt look gooey or thick, it was kind of watery if I remember correctly.

How old is she?
Has she been seen by a vet?

She will be 5 in May. I haven't taken her to the vet about this yet. I was trying to find out if this was a serious thing or if it would pass soon. Tonight I've noticed she seems to be sleeping more than usual. She usually comes to my room and sleeps with me most nights but hasn't in a few days. I really had no idea a sneeze could be serious but now I'm thinking it could be.

It's worth getting checked out. Usually it's not serious, but there can be instances of problems. My kitty has some sort of nasal infection, possibly caused by a bone infection, which we are trying to treat (though it has been difficult, since Spot doesn't do well on the antibiotics prescribed by the specialist, and we had to discontinue them). It's best to get it checked out early so it doesn't progress to something more serious. If it's a herpes viral infection, there are supplements, like L-Lysine, that can help ease the symptoms and prevent recurrences.

Thanks for your help. I will take her to the vet as soon as I can. I will post any updates.