I have a 2 year old hen (one of four) who seems to be sick. This is my first time having chickens and I'm at a loss. She was healthy, laying an egg daily, eating all of her food, etc. until she molted. She has not been laying at all since then (it's been months). About a week ago she started looking a bit listless and was sitting alone. We checked her vent and it looks like she has been having diarrhea. She's eating...but not as much as usual. She seems to be drinking. All of the other chickens seem to be fine...laying regularly and eating/drinking. What to do? This is my granddaughter's favorite chicken. Help! And thanks.