I have notice my 2 year old bard rock hen has gotten thinner. I have had them for about 6 months now and she was a full bird all this time. I noticed in the last 2 weeks she looks thinner? She still eats snacks and scratch so I assume she is still eating. Is this something that happens in the winter? Should I worm them? She is with 11 other chickens and they seem healthy. Is there anything I should do?