My chickens have started dropping like flies. I have no idea what is wrong with them. One minute they are fine, then the next time I see them they are unable to walk with their legs curled up under them. They still eat and drink just fine, but within a few hours they are dead. Ive lost 5 chickens and my turkey and a few more dont look so good. I have put Sulmet in their water today to see if it might be something bacterial. Very strange that nothing is different but they have suddenly started dying. They are not free range so they cant have gotten in to anything.