the cause of the bad breath has to be evaluated , it can be related to many factors like smoking , gastric problem, dehydration, diabetes, poor oral hygiene  periodontitis and many more causes . after that treatment has to be done .  for time bieng u can do scaling , scraping of tongue , use xylitol chewing gum ,drink more water , use mouth wash , hope it helps

You should get a complete scaling done. Use tongue cleaner after brushing your teeth (twice daily). This will keep the bad breath away.

You need to get your scaling and polishing ( cleaning of teeth) done. Then home maintainence by twice a day brushing, flossing and mouthwash should take care of your bad breath problem