I have heard some people say it's pretty hard to find Valbazen these days. I wormed my birds with Safe Guard Goat wormer. It doesn't stay suspended in water so you can treat them that way. But you can put it in their feed. @Texas Kiki , @Eggcessive should know the purpose dosage.
I would still go ahead with the Coccidiosis treatment with Corrid. It can't hurt them even if they don't have Cocci. You'll have to get @Texas Kiki , or @Eggcessive to tell you the dosage.
How long has it been since you've wormed the rest of the flock? If you never have or has been more than a...