My son's show Houdan pullet has been sick for 3 days now. She is gasping, coughing and sticking the neck forward and upwards. She wheezes when she sleeps and has crust/snot on her nose. I have been giving her 1/2 cc Tylan 50 for 3 days and Teramyacin in her water. She is not eating her crumbles, so I boiled her an egg and crumbled it for her and she picked at it today. Hopefully a good sign, should I do anything else? How long before I see any improvement? Is this something I should be concerned about for the rest of my flock? I have her in the house in a cage.