i have 40 chicks in a large homemade brooder, and have lost 6 in the last week. It is really sudden when one dies, like it is eating and drinking one minute only to come back an hour later to find it dead. Is it cocci? they are not vaccinated and don't eat medicated feed. any suggestions as to whats wrong? they are in my bedroom with 10 ducklings (seperate brooder) a few fish tanks, and a dog. i keep the thing really clean cause mom dosen't like the smell of it 
I've got 6 more chicks coming tomorrow...what should i do? i really don't want to lose anymore.

I've got 6 more chicks coming tomorrow...what should i do? i really don't want to lose anymore.