Last night I found one of my Black Australorp hens laying in the chicken yard slumped on her side. When I picked her up - I immediately noticed that she was EXTREMELY light and I can feel that she is skin and bones. She has been acting a little strange lately (approximately the last month) - she stays more to the outside of the flock, she's the first to go in at night, etc. But she's been eating and drinking along with the rest of the flock. She's been having trouble staying clean (I've been cleaning up her backside from poop), and a few weeks ago I gave her some Poultry Nutri-Drench thinking that a bit of vitamins would help. She's been better for the last few weeks and I hadn't noticed anything out of the ordinary until last night. It's obvious that she has been getting worse because she is so incredibly thin. I've pulled her out of the flock and put her in a separate crate. I gave her another dose of Nutri-Drench and her own food and water. She was so lethargic last night I was certain she would probably die overnight - but she's still hanging in there. Any ideas? FYI - I add food-grade DE to their food, bedding, and in the chicken yard to help keep things dry and reduce the chance of parasites and worms. The rest of the flock seems to be well - full-breasted, eating well, laying well, etc.