Last evening I noticed my 15 week old Australorp acting lethargic after being left out of the pen for their evening bug fest. As we continued to watch she also started sneezing, once to the point where we actually saw "snot" fly from her nose(not trying to be gross here). She stayed away from the others and didn't seem to eat. When it came it time to go in, we separated her from the flock. She is part of a group of 12, all about the same age. She is not wheezing and her eyes appear bright. We are starting her on antibiotics today. My questions are: 1. I have 3 separate buildings with different age chickens in. They do not come in contact with each other. Should I dose everyone? 2 .If I understand from what I 've read she will be a carrier if she survives. Does that mean I can't use or sell her eggs? 3. Will she pass anything on to any chicks? Any help would be greatly appreciated.