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.