Hi everyone. I have had my chickens for a year, and have had no health problems, until now. I bought some new chicks about a month ago from a local lady, one of them died about a week later, now all my chickens are sick, apart from one or two. the symptoms are, clear discharge from the eyes and nose, noisy rattly breathing, no egg laying at all, listless behavior, sneezing, a few have diarrhea. I assume this is some sort of respiratory cold or something? what should I do? I have a heat lamp on for them, but I have not treated them with anything yet.