All of a sudden over the past week or so Ive had chickens dieing from a very strange death. At first they seem fine then start getting a sort of limp. Then within a day or two they are totaly unable to walk and die soon after. Ive had 3 chickens in the past week die like this. I dont know what could be the cause. And its not directed at one pen or one breed. All of my chickens are having this problem. No matter what pen they are in or breed they are. Also they are full grown birds. If that means anything. They are not chicks and they are being kept on the ground.