A few days ago I lost a nearly year old laying hen. For the last week, she was super lethargic, don't think I saw her eat or drink, and eventually, found her one morning dead. I now have another, in a different coop, doing the same thing. Also almost a year old, and had been laying up to a week ago. Absolutely zero outward signs of illness, like eye or sinus issues. Just one day fine, next lethargic, a week later dead. Any ideas?