Here in post 17, it says to shake it well, and dosage is 0.13 ml per pound of weight. Give it for 3 days. Get a weight on your chick if possible.
https://www.backyardchickens.com/threads/dosage-for-toltrazuril-for-cocci.1427657/page-2
Is there any way to get the sulfa antibiotic from your regular vet, so it is started sooner? I will try to get dosage on toltrazuril since I have not used it. Can you tell me what the label looks like or where you ordered it?
If you get sulfa antibiotics, the common egg withdrawal time is 21 days, but it would not hurt to wait 30 days. Be sure to only treat the sick hen with those drugs (toltrazuril or sulfa.) A wire dog crate with food and water is how to isolate her, but keep her near the other chickens. Make sure...
I would start Corid now by a direct drench dose, 1/4 tsp. Then start the Corid in the water 2 tsp (10 ml) per gallon of water for 5-7 days. Is that the dosage you were using? Next I would get either the toltrazuril or a sulfa antibiotic such as Albon or sulfadimethoxine from your vet asap. You...