Where did you purchase them? They are suppose to get vaccine 24-48 hours. Were they around any other chickens that could contract virus? We had one get it. Was a horrible experience ! She did live for a few weeks. We had to hand feed her .... Was so sad!Mareaks disease, maybe. Did you vaccinate ? Has any of your chickens had same symptoms in past? It can spread up to 50 miles airborne. Just a thought, look it up on pedi poultry . It's a horrible disease! Sorry to hear.