Been suffering from bad breath for years. brush my teeth twice sometime even more than that scrape my tounge but after sometime my mouth start smelling again my tongue has always coated with yellow white thing and scrapping is not enough?

Halitosis can be caused by many things, including cavities, periodontal problems, acid reflux, sinus infections, and diet. Since you've had this problem for years, the question is have you seen your physician and dentist to be evaluated? If not, now is the time for consults. Please make the calls.

Common cause of bad breath is suffer-producing bacteria which can lodge between teeth (floss daily), in gum pockets (see your Dentist), in tonsil crypts (see ENT), on your tongue (use tongue scraper as instructed by your Dentist), in dental cavities (How long since last dental examination). Can also be from GERD or Diabetes or some blood dyscrasia (How long since you had a medical physical exam