Chickens can have coccidiosis infection 3 days before they show symptoms, so it is hard to notice they are sick at first. Two strains are very deadly (out of 9 or more.) The amprollium in your medication should start helping soon, but if they are not drinking it, you must give it to them with a dropper. Sorry for your loss, and I hope they start doing better.
Look at the text to the right of "macroscopic lesions"
