Sudden death, no signs

[Bigdawgs]

I need help quick! I noticed my rooster's crow changed a couple of days ago. Yesterday I found him dead. He was eating and drinking normally and his behavior was the same. He had no diarrhea,discolorations,swelling or coughing. He was about a year and a half. I went out today and found a dead hen whom was acting completely normal yesterday,and now I have another that is making strange vocalizations that I have never heard before. I am desperate to save my flock please help they have no symptoms,but they keep dying. Are the voice changes a clue?

 

[ArtGirl]

If it's a disease that's spreading I would try to stop it in it's tracks and separate the ones that show ANY signs of sickness so the others stay well. I'm not sure what it could be

but look up the symptoms for the chickens on the web and you can usually find what it could be.