My White Leghorn hen (2 years) was lying down in the run today on her side, her legs sticking out. I picked her up and she seems unable to stand. I checked her all over, and her legs seem fine, her vent, she doesn't seem egg-bound. I felt her crop though, and it feels like it's full of sand. It's very gritty and feels like she's been eating stones or something. Is is supposed to be like that? She is very weak and cannot stand is and gasping for breath. I got her to drink some water. She also smells odd. What could this be and what can I do?