Saturday night when I went in to feed and put my birds to bed, I noticed that one of my hens was careening crazily around the chicken coop and slamming into things. I moved her to a solitary cage and she is eating and drinking ok. Seems to be pooping. I don't feel an egg or anything else wrong with her, but I'm not sure what to feel for. When she tries to stand, her fanny goes up in the air and she topples over in somewhat of a somersault. I noticed yesterday and a bit more today that her right foot is starting to kinda curl up instead of lay out flat like normal. (As in her toes are curling under her foot basically.) Does anyone have any clues as to what would be causing this? I'm honestly not sure how old she is, maybe 3 or 4 years old? I've added and lost quite a number of birds over the years due to puppies and unknown assailants, but I believe she is one of my last bunch of chicks that I got about 3-4 years ago. All of my birds are free range, and I feed them lay mash and scratch that I buy in bulk from the local feed elevator..