On Jan 29th I got 3 new pet chickens, younger than the 5 other chickens I have. After I let the chickens out of their coop this Monday I heard one of the older ones making noise while breathing, even more so as I chased her around to catch her, the right side of her face was also a tiny bit swollen so I seperated her in my room from the rest of my flock. The next day as i checked up on my other chickens another older one, my bantam, starting making similar noises when breathing, i tried keeping her away from the rest as well but then that same night I heard my Australorp (again one of my older chickens) making the noise as well. So now i have 3 chickens making a "gargling" noise when breathing, bantam having more of a runny nose while the other two look mostly clean, all sneezing. I noticed they make the most gargly noise when i handle them. Unfortunately I have no more room to quarantine the big Australorp, she's outside with the others while i have the bantam and claret in my room. Is it possible that my older chickens got anything from the new ones even if they don't have the same symptoms other than one of them have had a slight runny nose, no gargling? I noticed her runny nose a day or two after getting her, now for the most part her beak looks clean. Did this come from something else? How quick do chickens catch something from a new bird if it's sick? I took the claret to a vet yesterday and we're trying antibiotics that they gave me for a week. Getting those 3 new chickens and switching to starter/grower feed is the only drastic changes I've done with my flock so far. I also have an aviary outside that houses doves and a few other birds, is it possible that whatever my chickens are having can spread onto them? They free range all over my backyard.