Thanks for asking the query,Bad breath
can be because of sinuses
, respitory tract infections, tongue coatings, food lodgement. decayed broken tooth, GIT disturbances.
I would suggest you to go for complete physical and dental examination.
Go for complete mouth scaling and polishing.
Clean the tongue with a soft bristle toothbrush, brush twice daily.
Take complete balanced diet, drink plenty of water and keep yourself hydrated.
Hope you find this as helpful,