If you can't get the poop checked for cocci, I would go ahead and treat for it with Corid, which you should be able to get at a feed store, as its quite possibly what is taking out your chicks. But the best way to go is definitely to get the poop checked by a vet, as dawg days..
Corid dose...
What I've read is to swab deep in the chicken's throat with a Q tip to check for gapeworm -- or you can look way back with a flashlight. If they are present, you will come out with thin red worms on your Q tip.
This is a thread about gapeworm, which requires a paarticular type of dewormer...