Fatty foods can cause pancreatitis. Pancreatitis is a very serious, often lethal condition. Does he normally eat only dog food and feasted on pork? Is he used to table food at all?
If he's crying out in pain, give him the vet's medicine, or leave him there for them to do it. That's very, very serious. He probably needs to be fasted, as well.
Mischeif N Miracles, CGC, RE (PRT, 10/13/2003)
Libby's Monkey N The Middle (Chinese Crested, 1/26/2008)
Teenie Weenie at the Bridge (Dachshund, ???-12/28/2007)