I have spent hundreds of dollars at the vet. My silkie chickens are dying one by one of coccidia. I had gone several weeks without a death, then had a sudden death today. He died at the vet in my lap. I have used corid, sulfamet, sulfatrim and still he died. I did not use the two sulfa drugs back to back of course. Any other ideas ? I am down to eight chickens, and can't take much more of this.