Found one hen not well this morning, she was standing alone with ruffled feathers and her head tucked in her back. I imediately took her out and gave her Tylan, and her feed. She's ate. Now she is standing, or barely standing with one foot completely bent backwards, under her leg. So she is standing on her ankle. Please tell me what this could be, and how contagious. I must add, I brought a hen home last weekend from a friend, and right after that my friends chickens got sick, some died imediately. None had the sypmtoms like mine, maybe hers had respiratory. I brought the hen back a few days later. Any advice or clues as what this is, would be greatly appreciated!