Yesterday I found blood in my pen where I have my 4 month old chickens housed. Today I find one of my little chickens dead and blood coming from its butt. I am wondering what this could be? The chickens are house in a wire cage about 3 feet off the ground. I feed them grower feed and fresh water daily. Some of the other chickens in this pen are losing their feathers like they are molting. I have checked for mites and have dusted them. I did not see any mites or flees.