I had the same problem with my little one who is now a year. She was sick as a kitten prior to us buying her and soon after she came home had a nose that was so crusty, green, and clogged ALL the time. Poor little thing. Our first vet waved it off as feline herpes--
but his lack of concern or desire to give her a blood test didn't feel right so I went to a new vet who did a work up on her of blood and x-rays. Her white count was up significantly, but she gained not lost weight and was as playful as ever. Although she ate a full bowl at feeding time, that only happened when I finger fed her because she could not smell her food from the congestion. We tried a couple different types of antibiotics over the last year and she's gotten better each time, but the raspy breathing and sneezing continues to come back randomly. Vet finally decided she has Chronic Rhino-sinusitis (CRS). I looked it up and it all fits her symptoms. But now I know what to look for and nip it with home treatment before it gets too bad for her.