A few days ago we noticed our 3 year old Issa Brown had her head pulled into the rest of her body. She wasn't walking much but she could walk. As of today, she is listless, not eating, falling over when she tries to walk. We have separated her from the rest of the flock with a heat lamp, food, water with some apple cider vinegar, yogurt and fresh fruit. Any idea what could be wrong with her? I saw her poop yesterday - haven't today, but I just got done with work and haven't been on poop watch.