Sounds as if he has a cold or allergies. Call the vet first and ask what the protocol is for what they think could be wrong. My cat has had colds and allergies and they went away. How long has he been like this?
I don't know but it sounds like you should see a vet pretty fast.
Sounds like your kitty could have an upper respiratory. I would advise you to call and get an appt to your vet on Monday . The only way of treatment is antibiotics.
cats can catch resp. Viruses, and infections, as well as have allergies. take kittty in to the vet. Soon.