I believe I have a respiratory illness problem. I have a flock of six chickens. About 10 days ago I noticed that one specific Australorp started coughing (after a high wind day though). A couple of days later two more were coughing. I isolated the Australorp who was having the most problems and began treatment with Tetroxy HCA-280. I also gave all of the other chickens the Tetroxy starting that same day. After a day or two of antibiotics the main flock was done coughing and they have shown no other issues such as runny eyes or smelly heads. The Australorp's eyes started showing small bubbles two or three days into antibiotics and she sounds a little raspy like a smoker. Now it has been six days and her eyes are pretty clear and there's no coughing but she still sounds slightly raspy. My question is whether or not everyone thinks I should be very concerned about the Australorp's raspyness despite showing no other signs of illness? Also, when would you feel safe introducing her back into the main flock?