I have a polish chicken about 4-5 months old who a little over a week ago started limping. Originally I thought she’d hurt her leg but it seems like both her legs are struggling and she’s having a really hard time walking or standing at all. She tries but sort of wobbles and falls. I’ve checked for mites, injury, bumble foot, and see nothing. Her legs look normal. All of our other chickens are acting completely fine. She really is acting ok and eating and drinking fine but whenever she tries to walk is stumbling and cannot hold herself up well. I don’t know what to do any ideas?