Hi Dear, As per a periodontist (gum specialist) my opinion wud be... You need a deep scaling. Usually pockets and deposits over teeth cause bad breathe. Which would be taken care by a simple deep Scaling.

Do u also clean your tongue?also do you have constipation gas or acidity? Even these things also do matter..also any unfilled cavities? Or presence of tartar?

Mere tooth brushing does not help you to get rid of the bad breath but a proper technique of tooth brushing twice a day plays a important role in maintainance of oral hygeine.  So first visit a dentist ..he will arrive at a diagnosis and bad breath may be due to multiple problems like deposits on the teeth , infection in the gums , decayed tooth etc ....