Bad breath, medically referred as halitosis, is brought on by excessive bacterial activity on the tongue in most cases (85%-90%), and gum disease which produces high levels of foul odors mainly due to the breakdown of proteins into individual amino acids, followed by further breakdown of certain amino acids to produce sulfur compounds. The stomach is considered by most experts to be a very uncommon source of bad breath. It is because the esophagus is closed, and a reflux serious enough to be bringing up stomach contents between the stomach and the esophagus indicates a health problem (i.e., gastroesophageal reflux disease or GERD). That said, only an extremely small percentage of bad breath problems may arise from stomach and digestion problems.
Since halitosis is almost always caused by a problem in the mouth, home remedies used against bad breath, such as mints and gum, may only temporarily mask the odors but cannot cure your bad breath. Eliminating the source of halitosis is an effective solution. I recommend that you visit a dentist
first. If no oral cause of your bad breath can be identified by the dentist, I suggest an appointment with a primary care doctor
(GI) to be evaluated for underlying reason for the potential stomach problem or any other condition that is causing your bad breath so that you can be treated appropriately.