Respiratory diseases can be hard on chickens, and can be caused by viruses, bacteria, or by fungi from mold. Most disease symptoms can last weeks, and complications or secondary infections may occur. Tylan is one of the few drugs that will be useful, but only affects a bacterial illness. Are you using Tylan 50 injectable, and how much are you giving? Your other chickens may get it, or may have been exposed the same time as she did. Make sure that she is taking water well, keep her from chilling, but not too hot, and make sure her nostrils are clear. Can you tell us what symptoms she has? Gasping, wheezing, rattly breathing, nasal drainage, eye drainage or crusting, and a swollen eyelid or face may be possible symptoms.
