Thanks for asking the query,
and bad breath is usually due to gingivitis which is associated with many factors
microorganisms, poor oral hygiene
leading to plague and calculus deposition, food impaction due to faulty restoration and appliances, mouth breathing
habit, nutritional deficiencies, endocrine changes like menstural cycle, pregnancy, diabetes.
I encourage you to visit a Dentist
to find out the exact cause and to get the teeth cleaned.
Brush your twice daily with a soft bristle toothbrush.
Replace your toothbrush in every six months.
Use antiseptic mouthwash solution gargles like chlorhexidine
Take vitamin suplements.
Include vitamin C containing food in your diet like lemon, oranges.
Hope this helps out.