I have a 9 month old blue orpington hen that is acting very lethargic. Normally she is on of the most active birds (of 10) when feeding. She lays regularly too. Today I found her laying in the floor of the coop sleeping. I let them out to stretch and feed and she only went out after I woke her. A little while later she was back inside laying down again. I'm still new to chickens so I don't know if I should be concerned or not. This is a sudden development.