This happened to one of my friends dogs often as they too would let the dog run free in the day. Come to find out the dog would would go to the neghbors house and eat a bunch of bread the naighbors would put out for the birds. They then built a fenced in back yard for the dog. I know it is hard to tell (or actaully have them listen) other familly members or friends not to let your dog run free but try again! Chewy might be getting into garbage or something harmful. good luck!