i read up online about how you can give goats vitamin c and it will boost there immune system so i gave it to our goat with corn (he wouldnt eat it any other way lol) and he got better! :)
I am unexperienced with goats, so I suggest you call your veterinarian. I know that when horses are purchased at auction, they are in close quarters with many other horses and can become exposed to various illnesses. I suspect this is the case with your goats. It would be wise in this case to get your vet out and see what is going on, but also to get an overview of your goats' requirements for healthcare, including vaccines, as well as any nutrition or other care questions you may have. Sorry I cannot be of more help. Keep us posted!