Earlier this week, one of my Plymouth Rocks died. She had been showing signs of sleepiness, lethargy, labored breathing, extremely thirsty and not interested in what the rest of the flock was doing. I had separated her since the flock decided to attack, but she died within a day of being separated from the flock. Now another one of my Plymouth Rocks is starting to show the same signs. (extreme thirst, sleepiness, lethargy) I've looked up all kinds of chicken diseases but can't pinpoint exactly what this is. I'm afraid it might be bird flu. Any suggestions would be very helpful! My Plymouth Rocks are 3 years old. Thank you!