I have 23 chickens. 2 White Leghorn roosters, 1 White Leghorn hen, 2 Black Ausssie hens, 1 mixed breed rooster and 19 Production Reds. These chickens have been outstanding all winter here in Eastern Oklahoma. I have been getting 15 to 21 eggs each day all winter long. My concern is on 1-28-2014 I found the White Leghorn hen lying on the floor of the chicken coop almost frozen. It was 5 degrees here that morning. She quickly warmed up but never recovered enough to put her back with the flock. She eats and drinks well, has normal droppings but, seems to suffer from vertigo. This morning one of the White Leghorn roosters was also having symptoms of vertigo. I brought him into the house and put him in the coop with the white hen. He too eats and drinks well but is staggering around as if he is very dizzy. All other chickens seem well at this moment. What do you think?