Thanks for asking the query,
Bad Breath can be because of various reasons,
Plague and calculus deposition , periodontal infections, tongue coating , xerostomia
, faulty restorations retaining plague and bacteria , oral pathologic lesions , mouthbreathing habit, fasting and starvations, eating of food like onions , garlic
Diseases of GIT , GERD , Nasal infections like rhinitis, sinusitis
Pulmonary infections like Bronchitis
Systemic conditions likediabetes , dehydration
Vist to a Dentist
and get checkup done .
Go for complete mouth scaling and polishing.
Drink lots of water .
mouthwash gargles twice daily.
visit to a GP and get checkup done.
Maintain a good oral hygiene .
Hope this helps out.