It could, indeed, be your own imagination. This makes up about 10% of those who feel their breath needs help. However, if you are in the other 90%, there are various things we would suggest. First, there could be a health condition that contributes. If you have not had a recent physical with your physician of choice, we highly recommend it.
Next, we need to consider your tongue. It harbors 85% of the bacteria in your mouth, and if not cleaned regularly, volatile sulfur compounds (VSCs) can proliferate and create an odor you are uncomfortable with.
Regular tongue scraping with an instrument made for that task is helpful. Another method for ridding your mouth of those VSCs is by rinsing regularly with a stabilized chlorine dioxide mouthwash. These can be bought through our office. Unfortunately, the 3 companies who make them are all multilevel organizations, so the stores do not carry these.
One recent discovery is the use of an herbal combination called "Tooth and Gum Tonic" put together by a small company in Ohio. An independent research organization tested a variety of mouthwashes, and although the chlorine dioxides outlasted other alcohol mouthwashes, Tooth and Gum Tonic fared even better. We have this in our office as well, but we can get you the address if you wish to order it yourself.