This was a problem we encountered a couple days ago, come to find out, he had hair entwined in his teeth and was rotting in his mouth, every time he licked himself the rot smell got on him, we had washed him on the outside but found the odor was coming from inside, after I removed the hair/fuzz from his bottom front teeth and the gums bled a little, the odor left! Even the odor left the other dogs because he was play biting on them (spreading the odor from his teeth)
Make sure your dog does not have an ear infection. Check for this by smelling inside the ear and if the smell is coming from there, then this is an ear infection. For an ear infection, you will need to clean the ears out thoroughly, and then have a vet prescribe a medication to treat it.
The dog could also have a yeast infection, which due to it's fungal nature will cause the dog to stink. If the smell is coming from the dog's skin, then this could be the cause.
Some dogs get very stinky when they get internal illnesses. For instance, kidney failure will cause a dog to stink as they have a lot of waste material in their bloodstream. Diabetic dogs will also start stinking if they have ketones in them.
Dogs can also start stinking because of their anal sac. This is a small gland near their anus that has a pus like discharge which is usually discharged when the dog relieves itself, but sometimes this won't happen. When the dog is not able to empty the sac itself, then this needs to be done for it by a vet, and the collecting pus can cause a bad smell.
