Give them a vitamin, scrambled eggs and chick grit. Also, let them peck a bit of plain yogurt from a spoon twice a day. Do not let them eat too much though.
It is normal to have to clean the pasty butt for three days or so though. Their normal food should be a good starter too.
Will the medicated chick starter feed help? Is Corid too strong for chicks? I received a 3-month old shipped and as it's my practice I took a fecal sample to vet and she was positive for cocci. She was on non-medicated chick starter so for medicating her we're using Corid. She's new to us and not really into yogurt or fresh produce yet. First couple days she was lethargic but she's moving around normally again after a couple days on Corid - vet recommended 21-day treatment. Sometimes blood in poops lets you know if you have one of the strains but there are so many strains of coccidia that without a lab test you can't really know for sure if a chicken has it. My vet said that if chicks/chickens are sharing feed that cocci spreads that way just as much as picking it up from poops or soil. Poor chickens have so many things that they can contract. I pulled up a website on chicken diseases and was overwhelmed at everything that they can contract.

