My olive-egger hen (about 5 years old) is very lethargic and wouldn't get off the roost this morning. I picked her up and she just felt very limp. She is usually the head of the flock and very fiesty. Her head was alert and eyes clear. No raspy breathing or build up in nostrils, etc. Her vent is clear but I did notice there were some green goopy drops of poop on tips of feathers & down where the poop usually drops while they are on the roost at night. She just started laying again for the season and we got about 4 eggs from her then skipped yesterday and this morning. She usually skips a day, sometimes two, during the week and is my best layer. I thought maybe she might have an egg stuck but I don't feel anything unusual near the vent area. I do feel a larger-than-usual puffiness, like a water balloon, a little further back from the vent (area under her legs). I do not feel anything hard like an egg stuck in there, but I am not sure what I am looking for since none of my chickens ever had an egg stuck before. When I put her back down. She slouched over to the corner and put her head down. Her tail would slowly and slightly pump up and down the way a human's chest would move with breathing. I am not sure what else to do. Can this be a sickness like a virus/bacteria she caught or is there some other function of her body gone wrong? She seemed fine yesterday. I have 3 other hens (for a total of 4 birds) in my flock who are all acting normally. What's the next step?