Did you ever figure out what caused it? I bought some medicine to put in the water for the rest of flock, but the stinking polish was almost fully crested out. Oh well I still have one more going strongAww, so sorry to hear that! The same thing happened to me one day with one of my hens. Opened the coop, and there she was. No indication of anything being wrong and all of my other hens were and still are healthy.