One of my (almost) 6 month old Buff Orpington's suddenly developed a limp a few days ago. She holds her right foot up whenever she stands and doesn't hardly do anything anymore. We've checked and can find no outward signs of injury. She's getting more and more lethargic and today is barely even moving. She doesn't even move or fuss when I pick her up (highly unusual for my hens) and even lets me turn her upside down without a fight to check her leg. When we came home from church tonight she was laying on the ground in the run underneath the waterer. (haha Is that a word?) Anyway, she was not roosting in the coop with the rest of the hens. That's never happened before. We brought her in the house to keep an eye on her, but we honestly have no idea what to do. Any advice?