I have 20 Isa Browns that are 5 months old. One died yesterday, 2 today. Their vents were bleeding and most of the other 17 have blood around their vents as well. One week ago I added some other chickens I hatched 3 months ago. I have since seperated them again, it did not go well. I don't know if they had some disease they never had any symptoms and the 3 month old ones have no blood. I am new to having chickens and would appreciate any help.