We have 25 healthy chickens raised from chics. We recently bought 6 new hens that were already laying. Day three we found one of the new chickens dead (no signs of anything wrong), 2 days later one of the original 25 appeared very docile and made a low moaning noise, the next morning she died, no outward symptoms of sickness. Now one chicken appears to have muscus in it's eyes and is acting docile as well. What should i do? After the death of the first chicken i seperated the new ones from the original 25 but it appears i was too late. We are new to raising chickens, any help is appreciated.