We have chickens that are about 5 months old, we got them in August. In October we got baby silkie chicks from some people. Not too long after we got them, one just died and at the same time another seemed to play opposom. I thought it was dead but it got up, went down again and got back up and has been fine. This past Thursday night, another chick was dead and one went missing. We found the missing one dead in to coop the next afternoon. Don't know how it got there because it was there running around when my son went to take care of the chickens that night and when he went to grab the chicks to bring them in for the night it was missing. We searched everywhere and I searched all morning yesterday in the coop around the property 4-5 times and didn't find him until around 3 pm dead in the coop. Yesterday I noticed that one of our older chickens (5 month old one) had it's head shrugged down, like it's shoulders were up and had no neck. It's face was up. It was walking around and eatting and drinking fine and sitting on perches. This morning my son came in with this chicken and said it couldn't stand up. I took it out side and set it down in the grass and while I was still supporting it, it put one foot down but held the other up. I thought it's leg was injured but then it put the foot down and I could feel it using the muscles in it's leg, but it was very unsteady and didn't move. I put it in a cage and in our basement under the heater thinking maybe it's cold, but I don't know. It's able to stand, but it's holding it's head down and wont open it's eyes. It's head slowly lowers and then it jerks it back up like someone sleeping. HELP! I don't know what to do or what is wrong. I'm losing my chickens. I just wanna cry. I did notice yesterday, I took my last silkie chick inside (who looks completely healthy) and gave it a bath because it was disgusting and noticed it had fleas or mites or something. Could that be the problem?