What colour is your tongue?
What does the breath smell like? ie
If it is sour then it could be caused by eating sour foods in excess or possibly other things. (difficult to say without more info) Do you eat raw? Do you eat fat? What sorts of foods do you eat? Do you eat sugar or white flour in any form, also grains?
If it is like old rotting food, then it is likely you have food caught between your gums and teeth or very poor digestion. Again difficult to know without examining.
With the food between gums and teeth, brushing can help, brush from gums toward teeth to push it out. Also get a tooth powder called Vicco Vajradanti at an Indian store
http://www.indiaabundance.com/shopping/sp36_pr1457/Vicco_Vajradanti_Tooth_Powder_Big.html It's cheap and reasonable quality.
You wet your index finger, dip it in the powder then rub it on your gums for two minutes, vigorously, but don't hurt yourself or scratch the surface. Be careful not to touch your nails on the gums. Push away from the gums towards your teeth. This will encourage blood flow, which will strengthen your gums and push out any 'stuff'. Then you close your mouth for a few minutes holding the saliva and powder in to sanitize your mouth, then rinse it out.
For a better choice get this
http://www.indiaabundance.com/shopping/sp260_pr1513/Maharishi_Ayurdent_Toothpaste_(3_Packs).html tooth paste.
Now for a strange suggestion.
When you defoecate (sh#t), sit down, lean forward so you compress your lower abdomen (thus forcing out the feoces) and put your teeth together and clench them slightly. This will keep your teeth from becoming loose. Get in this habit.
We first world people think we are so clever, having flush toilets, but they are one of the worst inventions ever made. They pollute our drinking water, concentrate wastes (which is a dangerous habit) and because we sit on a seat, we lose out on the benefit of doing like we should be doing, squatting to defoecate.
When you squat you compress the lower abdomen thus forcing it out without having to push, which if you leave your mouth open causes your teeth to loosen. We also gain a benefit from balancing on our feet with the body forcing the ankle to bend forward.
By not forcing it out, some residual remains which can lead to buildup in the colon with the attendent diseases. Some theorize that this partly explains why bowel cancer is endemic.... Who knows.