My husband and I are new to raising chickens. We moved into a home and inherited 2 full grown hens. Our son asked us if we could get more. We bought 5 baby chicks from a highly recommended breeder. Our chicks have grown up amazingly until recently. One of our chicks, the smallest one, died last week. We didn't see any symptoms except just getting lethargic. We just lost one today and looks like maybe two others as well. We believe its Mareks from the feedback we have received. They are losing the ability to walk and then die a couple days later. Does anyone know why this happens? Has anyone gone through this? Anything we can do to prevent or help it?