I have 31 chickens in the coop, 6 are a duel purpose breed and 8 weeks old the rest are Cornish cross. I came out this morning and one of the duel purpose breed chickens was almost dead. No damage to show an attack it just kind moves like its drunk and can't stand up. I am really scared I am going to Loos the entire flock or worry about sickness in meat chickens being passed on to me. How worried should I be?