Bad breath since i was a child, what to do?

Depends: It depends upon the cause. The most common is from the mouth and there are mouth rinses and tongue scrappers that work well.. Talk with you dentist 1st... And if there is no change, see your physician to rule out a systemic or GI problem.

Chronic Halitosis: Chronic halitosis may be from sinus problems\post nasal drip, GI problems, poor oral hygiene (regardless of how well you think you are doing), not using a tongue scraper daily, or a host of other medical\dental problems. Start by seeing a dentist to rule out dental causes, then physician for medical ones. Last resort are some mouth rinses to remove sulphur. See comment for website->.