New puppy strange odor

My new puppy has a funny smell it almost smells like onions. It is not his butt ears or his breath. I changed his food as soon as we brought him home and that hasn’t helped either. The smell is obviously coming from his skin but there are no signs of skin irritation or anything like that. I have an appointment with the vet Friday but I was just wondering if anyone has any ideas or has had a similar problem. I’ve had Corgis for 20 years and have never had this issue.