I have 6 hens, when we let them out this morning to free range one of them tried to come out but then fell down again she's VERY lethargic, eyes closed, and at her mucus membranes inside the mouth are pale, her comb is pale, her crop is empty, there is no visible sign of any external injuries. She was fine when put up last night. I have her on a heating pad on low inside with blankets now because she seemed a little cold to the touch. I have tubed her some fluids a couple times already. Does anyone else have any experience with there hen suddenly falling ill like this?