I have kept a very small backyard flock for close on twenty years but I am puzzled by the recent unexpected deaths of two of my flock. They were full of health in the morning and dead with no signs of injury in the afternoon. They died a week apart. The county ag agent had no suggestions and said an autopsy would be costly. I have searched my yard for a cause but have found none. I am down to one lonely chicken and have to decide whether to get new chicks or find her a home. Any thoughts on the matter?