Found her this afternoon with clear mucous in nostrils and mouth. Gasping for air. Breath smells like something "dead". Very noxious odor. Crop feels empty. Chick is rattling when breathing sometimes through nose passages. Took off medicated starter feed last week. Free range and have access to scratch feed as well as their reg starter feed. Lethargic and sleeping in my arms as I write this. Help with any advice, please.