Help Help Help!!!!! I've had 6 dead chicks in less than a week :'(

I got 16 chicks last week, 8 anconas and 8 ameraucanas. In the past 4 days 6 of them have died (a mixture of both breeds) I've added ACV to their water, made sure the temperature of the coop is high enough, and double checked that I am giving them starter feed. all seem to be eating and drinking. I will have checked on them, all seem fine, and then a few hours later come back and one is dead. poop all seems normall, except one is a little runny (but she is still alive). using paper towels for the lining of the coop and have a little boxed area with some shavings for them to snuggle up in.

at one point when i checked on them today one chick was laying on her side. almost seemed as though she could only use one side of her body....

i have no idea what is going on with them!! is it possible to get a bad group?? seems strange that both breeds are dying though.... any thoughts would be appreciated!!!