Three hens dead in a few weeks one at a time. They stop eating, drinking, roosting, get limp, stop walking , sit down and die. No vent blockage. Just get weaker and weaker. I e moved them to food and water but they refuse it. It's isolated to one at a time. I free range a few hours a day in a large yard but I'm surrounded by good neighbors I need advice and help. This is my first flock and my first problem.