This hen is 2.5 years old and has only been a sporadic layer of very small dark brown eggs this past 1.5 years. She came down sick yesterday, not able to stand up without losing her balance and ends up moving around in a crawl. Yesterday she was not eating or drinking but today she did drink water. Yesterday after trying to get her interested in her food with no success I moved her from the coup to their fenced in "daycare center" where she sat and at least showed some interest in pecking at the soil. When I put her in the coup last night I really expected that she would pass away by morning. The next day she seemed a little more alert but still in the same condition with the exception that she drank water and I gave her a fresh ear of corn which she ate quite a bit. I have one other hen the same age who consistently lays a large brown egg daily except for now as they are both molting. She is showing some concern for her sick sister but is active and well. They have a large well ventilated Aframe coup with half of it enclosed. I use white pine shavings and turn them over weekly, I just added new shavings to the existing last week. They get plenty of fresh water with a tsp of cider vinegar to a half gallon of water. They eat a custom blend of feed/scratch not pellets and this feed has not changed. Any idea or suggestions for me?