http://www.orabrush.com/index_C.html?gclid=CJvr89GL3rECFSFLpgod2UcA6w
The short video on this site gives a very helpful suggestion for determining whether your breath smells bad (in private!).
Most bad breath is easily ‘cured’ by scrubbing the back of the tongue with bi-carb soda on a toothbrush. It cleans the tongue which should come up completely clean and pink. Do each time you clean your teeth. Rinse out with water afterwards. Also swirl your toothbrush in some of the bi-carb soda water to clean the germs off it. Otherwise your toothbrush is a major source of re-infection.
This advice was given me by a top ear nose and throat specialist years ago and it is some of the best health advice I’ve ever received. It meant I didn’t have my tonsils out. It meant that months of (ineffective) anti-biotics for a yellow phlegm throat could cease forever. It’s been great for my health and breathing and keeping infections down.