Yesterday when I went outside to let my chickens out one was acting very odd. She had her tail feathers up very high and her bottom feathers down very low. There was a clear liquid coming out of her butt and it was inflamed. She was also holding her chest low but wasn't acting like she was in a lot of pain. I couldn't catch her so I couldn't really look at it up close. When my step-dad went down to the pin this morning she was dead. Can somebody tell me what might have happened so if it was to happen again I could help my chicken?