Today one of my lovely Buff orpington hens died suddenly, Here is some background and observed symptoms. Flock of 18 10 month old hens and one rooster. All of these birds have lived together since hatching Coop is 8x12 with a attached 400 sq ft run. feed is layer pellets, sunflower seeds and household spoilings Everyone was fine this morning when I let the birds out to the pen. This afternoon I noticed one hen who was having a hard time walking. She was stumbling and couldn't make it back up the ramp into the coop. Brought her into the house and put her into the crate for isolation, she ws very listless and didn't move around at all. Left the house and returned 4 hours later and she was gone . Eyes were clear, feathers looked good, comb looked normal. Her tail was down when I brought her into the house. There was a small watery greenish colored poop near her butt when I picked her up after she was dead. I checked on the rest of the flock and everyone was on the roost and looked alright. Does anyone have any idea what may have caused this death? I really don't want to lose anymore of my precious birds.