Stretch her neck out, open her mouth and look down her throat with a flashlight and see if something is stuck in her throat.Ther is a small trachea hole a couple inches down the throat simular to the ones humans have. Make sure it is not clogged with feed.Soak some bread in veg oil or olive oil and put small pieces in her mouth. If she eats it, give her a few more till she does'nt want to swallow anymore. Try bread pieces soaked in milk. It could be worms (gape or roundworm)or any number of things but you've got to keep her hydrated to keep her alive. Drop some water down her throat a little at a time. Try to entice her to eat with crumbled egg whites, canned dog food, sardines, tuna, apples or other fruit. Anything to keep her eating until you find the problem. Isolate her from the rest of the chickens and hand feed her. as soon as she starts responding to feed, get some Wazine wormer and make a weak dosage of it for her to drink. Keep Wazine AWAY FROM CHILDREN, but of course that applies to ANY medication. Try everything you can think of at this point for your pullet. Google her symtoms online.