My Rhode Island Red seems sick. She is usually boisterous, but in the last week seems lethargic and waddles. Her tail is drooping. She usually is excited to graze outside, but today she just hunched in the coop. She eats fine, though. Her poop is green and foamy, but that may be because of the vegetables. I felt her stomach and she seems bloated; it feels like a water balloon. What could be causing this?