A.D.
Could be a sign of infection. My husband had AWFUL breath. At my insistence, he went to the dentist to find out he had a crack in his molar (no pain) that was causing an infection. His wisdom teeth were pushing into his molars which caused the crack. Had his wisdom teeth removed, a cleaning, and fixed his cracked tooth and it immediately took care of the problem. I've also heard that sinus infections can cause serious bad breath. See a Dr. and/or dentist. Hope this helps.