That is so discouraging! There may have been an underlying problem. Lots of times Coccidiosis can overwhelm a chicken who has another issue...you treat for Cocci and they do improve, but the underlying issue does not go away. I agree, go ahead and treat the rest of the flock, and it wouldn't be a bad idea to deworm them a few days after they finish the Corid. Use a broad spectrum dewormer such as Safeguard, which should be easy to get locally. We like Levamisol, which we order through www.firststatevetsupply.com. As far as the Cocci, as they grow into adulthood, most chickens develop a resistance to Cocci, and you shouldn't use Corid unless you see a problem, because it is so overused it can lose it's effectiveness. My vet gave me an alternate medication to treat Coccidiosis, which worked well, so alternates are available, if you ever have a need. So sorry for your loss, but you certainly tried. Good luck in the future!
