Do a complete mouth cleaning regimen twice a day everyday: floss between all your teeth, scrape your tongue with a good tongue scraper, use a good mouthwash, and finally brush your teeth. And use mouthwash after every meal, or at least floss out all the grub then chew an Orbit gum for at least 15 minutes. If these don't work, then you'll have to visit a dentist. You may have a horrible case of Halitosis and it will require medication.
(My floss, scraper, brush, and wash are all of the Crest brand. I also use Crest White strips every six months and see my dentist twice a year. I've never had bad breath, but I hope these work for you).