What kind of medication did the feed store give you? How much of it are you using? Corid (same thing as Amprolium) is the best, most effective treatment. If you can't find that anywhere then Sulmet is the next best thing, but I have found that Sulmet does not work very efficiently and seems to weaken the birds more.
When my chicks get cocci, I isolate the ones that look even the slightest bit puffed up or lethargic. I put Corid in their water along with ACV. Even if they are able to drink, I still take a small syringe and give them 1-2 syringe fulls of the water every 2 or 3 hours during the day. If they aren't eating I give them a syringe full of sugar water or fresh strawberry squeezed into water with the syringe several times a day to perk them up. I offer them extra treats if they don't want to eat--healthy scratch (with whole grains), scrambled eggs, berries, cooked oats, yogurt, whole milk, defrosted frozen corn, etc. Once they start eating again I give them mash made with the Corid water, ACV, plain organic yogurt, and organic powdered milk.
By doing that I didn't lose a single chick to Cocci this year! (It seems to live in my soil, and despite my best efforts my new chicks almost always catch it in the spring...)
If all of your birds get it, don't panic. It's not an illness that has lifelong repercussions. After they get over it, they will be fine and immune to it.
