I do a preventative dose every 3 weeks for 5 days until the are 9 months. I don't see coccidiosis symptoms. Do that on one group of chicks and not the other, and you will see the difference. The one chick you had that showed symptoms? Do the treatment dose for 7 days. Let me know how the bird is...
That's difficult when the bird stops drinking/eating. You could leave water free choice and use the Corid-water mixture in the wet mash. I sure hope your pullet recovers.
If I were you, I'd do a treatment dose of Corid in the drinking water. The dose for Corid 9.6% solution is 2 tsp per gallon of water. The Corid 20% dispersible powder is 1 tsp per gallon of water. Treat for 5-7 days, then use vitamins and probiotics in the water for three days. Let us know how...