I'm not a vet but it sounds like an upper respiratory infection which are very common in cats. Normally for an adult cat they give a cheap liquid antibiotic (clavamox usually) but I don't know about kittens. I would call and schedule an appointment
You should probably call to make an appointment. We got lots of stuff done though for under $100 so it shouldn't be too much.
Best that you call.
Thanks! Your answer is awaiting moderation.