I have lost three hens, of all the same breed, in the last six months. All of them, before they died, walked with their tail down, more and more noticeably for a couple of months until they were nearly pointing straight down, got really bad diarrhea, and slept most of the time, they, then would just die. The breed is called "Red Star", which I get from a local feed store. None of this happened with the other breed I have. The remaining two of this breed are slowly walking more with their tails down and have bad diarrhea, they were two years old in August. Does anyone know what this is and if there's a way to stop it?