Actually similar symptoms have happened to other chickens in my flock the past year or so--all one at a time, never two sick together. They start by getting lethargic, sitting rather than walking around. I notice a messy vent. We clean it out as best as possible, separate them as well, but most times it gets worse. One led to fly strike and eventual death. This one I fear is on the way but I want to know why this keeps happening. Never to more than one chicken and always at least 2-3 months apart. See pics of current hen, a Barred Rock named June. Thanks for any and all advice!!