It could be you are also feeding too much canned food, the new food is upsetting them for some reason, and the human food...most vets will agree some human food cannot be tolerated by dogs. Some do ok but all dogs will get totally spoiled and not want anything but human food.
If their bowel issues continue it could be they've developed colitis. Our dog got it once when an elderly aunt gave him pork even though we told her it made him sick. He needed to have a course of antibiotics to end it.
So, I'd give our vet a call.