I was on vacation for two weeks with house sitter and when I came back one of my hens had lost a lot of weight, she feels like she weighs nothing and especially around her vent all her bones protrude. I've offered her plenty of appealing foods but doesn't eat much and sits around and is very weak. After picking her up and offering her food she started to drool/ throw up liquid stuff. She isn't improving after three days and is very sick. She also has a slightly white chalky stuff below her vent. Should I separate her from the others who aren't bothering her....could it be a parasite thought the other 10 hens are fine so far. Is is coccidiosis? Do I need to call a vet? Thanks so much, i'm very worried about her tonight!