If you have had the cleaning, addressed all dental issues, and brushing and flossing daily, it may be GERD. This is when stomach acids slip up into the back of the throat. Some people just have bad breath when they get up in the morning because they have not eaten and the body goes into starvation mode, burning the fat stores for energy. Also brush the tongue when you brush to remove odor causing plaque and bacterial by-products.
I recommend visiting one of the practiced dental hygienists to take regular dental checkup for avoiding the dental problem of breath stink.