The medicated chick feed will not treat coccidiosis. It’s meant to add small amounts of the virus strain to try and build immunity. But once coccidiosis is present, medicated feed is useless.
Just continue with the Corid treatment. Do the higher dosage for 5 days, then retreat after 2 weeks. No need to separate sick from healthy; treat then all regardless and don’t offer them any other source of water. Coccidiosis is EVERYWHERE; it comes from wild birds so just you going outside can...