What's wrong with your dog if you squeezed a fat white worm out of his side and it had a yellowish tint and what looked like dirt inside of it and the hole that it emerged from is not closing up?

you need to get that dog to the Vet and have it treated. =Answer= Sounds like your dog has had a wound and that worm is a maggot. When there is a fresh wound (even on people who are in an accident and not rescued for days) flies will lay eggs in the wound and this turns into maggots. It's sounds gross, but maggots eat dead and rotting flesh and on many occasion have saved a humans life and, in some hospitals in different countries (also especially during the Vietnam War) they would use maggots to eat infected and dead flesh. It's best to see a vet and I am sure the wound will be reopened and cleansed and treated and your dog will probably go on antibiotics. When in doubt ALWAYS take your pet to a vet.