I'm worries about my Buff Orpington Hen. She's about 6 months old. She's been acting lethargic, to the point of not holding up her wings all the way. She's also not roosting with the other three, instead choosing to roost on the side of the nesting box. She's still out and about but slow to catch up with the flock. She's eating, drinking and pooping and I don't see anything weird in her poop. Please help! Thanks so much.