I have 23 chickens and all of a sudden a lot of them are occasionally sneezing and coughing and having trouble breathing. I've done some research and it could be influenza or some respiratory disease but it seems like it's starting to get worse and more birds are beginning to have similar symptoms. I'm very worried about them! We take good care of our chickens: 16'x20' house, heated and such, roosting, nesting and window, and ventilation. they have a huge closed in run outside that they are let into every day. We clean their poop out everyday, clean water, and food. I really really really don't want to loose my whole flock so any advise would be soooo very much appreciated. They are New Hampshire Reds, Aracaunas, and White Plymouth Rocks...and they are all 7 months old!