After you worm your birds, mix buttermilk with plain boiled white rice and give it to your chickens to eat, make sure the mixture has cooled down. Buttermilk is a better probiotic than yogurt. It coats the intestinal lining preventing further damage by cocci. It can be used as a temporary treatment for cocci until corid can be given. It will also stop diarrhea, unlike yogurt which tends to pass through them. Boiled white rice "settles'' innards. Your chickens will scoff it up, the white rice looks like maggots to them.
Do this after each worming. You wont regret it and your chickens will love it.
I also give our dog boiled white rice sometimes when he's off his food. Rice settles their stomach and gets regular eating habits back to normal.