Approximately 85% of bad breath/halitosis cases are a result from oral conditions. Anaerobic bacteria are responsible for bad breath because they produce sulfur products that are volatile and readily expressed. Good oral hygiene is a prerequisite for preventing bad breath caused by debris and bacteria that make a home in your mouth. To avoid food collecting and remaining in your mouth over night and fermenting I suggest you purchase a water pik device and use it before retiring each evening. This will prevent debris from causing any of the issues you are now experiencing resulting in any odors. One of the most common causes of bad breath is dry mouth or sinus issues. Dryness of the mouth is called Xerostomia, and is common as we age. Dry mouth could be due to a reduced salivary flow causing the dryness of your mouth which results in bad breath as well. Dryness of the mouth is called Xerostomia. Biotene is the most prescribed medication for this problem and it is available over the counter at any drugstore.
This is website for it: http://www.biotene.com/
Other OTC saliva substitutes include Moi-Stir, Optimoist, and Mouth Kote.
Sinusitis, Deviated Septum and Tonsillitis are also possible causes of bad breath.
Digestive issues can also be a cause of bad breath especially if you are having issues at the time of the bad breath.
Acid Reflux (gastroesophageal reflux) can also cause halitosis. Tests like barium esophagram, pH monitoring, and endoscopy are commonly used to identify possible causes of acid reflux.
Some medications when ingested will release odors that are excreted when breathing. These odors occur from metabolized product from the liver and then are excreted in the air.
Which is why systemic illnesses like liver failure, uremia or kidney failure or diabetic acidosis can lead to bad breath.
Your first step would be to treated by a dentist/hygienist with a thorough cleaning and debridement
. After eating you should rinse your mouth with water to help dislodge any remaining food particles. Also use a soft plastic tongue scraper to clean the surface of your tongue. Strive to eat a high fiber diet. If after altering your oral hygiene and using the water pik regularly you are still experiencing bad breath then your next step would be to contact your physician for a work up to determine what else could be causing your problem.
Hope all this helps.