Bad breath that continues even after scaling may not be related to teeth or gum problems.
The most common cause of bad breath other than gum infection is dry mouth ie dehydration. Lack of saliva in your mouth also causes bad breath. Keep yourself hydrated, drink small amounts of water often. Chewing sugarfree gums often also keeps your mouth hydrated.and scaling ideally should be done every six months.
If this does not help, other reasons could be - gastritis ( acidity) ,
diabetes or other systemic illnesses. Get a evaluation by physician