I have a 4 month old pullet who in the last week or so has had one of her eyes starting to droop, and now is slowing down and not keeping up as well with the other chickens. She looks unsteady, like her legs aren't working as well. Also, it looks like her head is crooked around her eye. I am wondering if it is Marek's? I am a first time chicken owner, so I need some advice... Thanks!!