Hello sir,
Bad breathe is due to many reason like plaque calculus, gastric problems, starvation,
diabetes , dehydration , any decayed teeth causing food lodgement.
You will have to check for the cause and treat accordingly.
If it is due to plaque a proper scaling and root planning is advice followed by brushing 2 times daily, use of mouth wash , using floss .
If due to any decayed tooth treatment of that is required.
Next Steps
consult a dentist.