There are so many different things is could be and hopefully it is just one of another respiratory ailments that isnt as infecitous. If you treat and have more that develop the same symptoms you may need to know what you are dealing with. My understanding is that Infectious Coryza when treated and survived will still cause birds to be carriers of the disease. I think there is a vaccine ? You are lucky to have a vet that will tend your chickens. Here we dont closer than about a 3 hour drive. Keep us posted..I've done tons of reading. Maybe I'm just not looking in the right place. But the Infectious Coryza seems to fit the bill perfectly. We do have a vet appointment for next week. Didn't think it would hurt to ask anyway.