Info: The hen is approx. 18 months old, she lives with 26 other hens and one roo, nests are straw, yard is dirt (rain the past few days has made it a bit muddy), allowed to free-range several times a week, food is layer pellets, scratch grains, and veggie scraps for treats. I've had these birds for about a month and I have not treated them for worms/mites/fleas or anything else. I don't know if the previous owner ever did any of that. I don't know if she has been laying since I have so many I can't tell who lays what, same for poop. This morning while all the others were at their first feeding she was off to the side by herself, standing real still and closing her eyes like she was sleepy. Later in the day when I checked on them again she was on the bottom shelf (our nesting boxes are a re-purposed canning shelf) just sitting in some straw, sort of limp, not like she was about to lay. I picked her up and she just cooed a bit like she was in pain. I'm not exactly sure what I should have felt for but I felt her all over, she does not seem to be egg-bound but she feels very light and limp. I looked for evidence of mite and such but I didn't see any. Her vent seems normal, her comb seems normal, around her eyes is a little pink but I think they are all like that. She's breathing fine, not coughing or wheezing, no runny or discharge in eyes or nose. She's just lethargic and slow, uninterested in the evening treats, and she didn't join the others at roosting time, she just closed her eyes and laid on the bottom shelf. Here's the thing: I've read about 30 threads on here about hens with all the same symptoms. In every single one after a few hours or a couple days they come back and say the chicken died. I lost my duck to a predator a couple weeks ago, but something like this will break my heart. If I don't see vast improvement tomorrow morning I'm going to isolate her from the others, although she is already avoiding them. I probably should have done that tonight but I just didn't have the heart. Does anyone have any helpful advice, besides checking for worms/mites/fleas. I have a hard time believing that there is this silent killer that drops chickens with no apparent reason and nobody knows why. Like I said, I've read a ton of posts and the only thing anyone offered was condolences. I'm probably going to bawl like a baby if I lose my poor little hen. Thanks in advance.