I noticed one of my older hens staying "in bed" a couple of weeks ago and not moving around as much. Now she won't walk at all, has not ate or drank in two days,and not even able to stand on her own. I have been worried about what this could be.Also, before she quit walking...her vent was caked up bad. I washed her off with warm water, but she quit walking that same day. I really need some answers and need to know what to do to prevent this from happening to the rest of my flock.