In my case, this was the source of my problem - my tonsil stones
However this information can be misleading – tonsiloliths are not always the source of your problem. The smell from tonsil stones is actually contained within the tonsil stones themselves. Unless it actually breaks open in the back of your throat, this odor is not usually released.
But (and this is a big but)... if you are creating tonsil stones (and thus the foul odors of methyl mercaptan and hydrogen sulfide), then you have the exact oral environment to cause bad breath, existing in the back of your throat and tonsils.
Thus, in most cases, people with tonsil stones, also may have a breath problem – either occasional or chronic. This is because the exact conditions that cause tonsil stones (post-nasal drip, dry mouth, white tongue, excess mucous), and also very likely to create breath problems.
For more information on the numerous things that can cause bad breath, I highly recommend taking a moment to download a free ebook called The Bad Breath Bible. This highly informative ebook, written by Dr. Harold Katz, tells you everything you need to know about breath issues, and how to stop them.