Yesterday my 1 yr old cochin/frizzle rooster was limping with his right leg. I examined him and found no visible injuries. I moved the leg and checked the joints and found no injuries. He otherwise looked fine and had no other signs and symptoms. I left for work in the evening and when I returned home in the morning he was dead. He had a very small amount of clear thick fluid coming from his beak, that appeared to be vomit as it was not frothy like from the lungs. All my other chickens appear healthy and I have not had any recent deaths. What could have caused this?