bad breath

I have been suffering from halitosis for almost 20 years.  My dentist has told me I have a very very clean mouth, no cavities.  Dentist tell me bad breath cannot come from the stomach which I believe I have.  I am lactose intolerance. Now it seems that everyone is talking about sulfur compounds causing bad breath.  I have tried all of those types of mouth washes and tooth paste.  There are others like myself who have this problem as we have a web group where we share possible solutions and cry on each other shoulders.  The reason I belive bad breath can come from the stomach as a result of food has is based upon what happens when you eat garlic or people who are alcoholics.  The odor is expelled from the lungs.  This information I am pasting in summarizes my theory.  If you can shed some light on this problem I would appreciate it as well as others.  

"The fermentation of nonabsorbed carbohydrates exposed to certain intestinal bacterial results in the production of hydrogen (H2) gas within the intestinal lumen, a fixed portion of which is reabsorbed and excreted by the lungs. Approximately 21% of the colonic H2 gas is excreted by the pulmonary route. The breath H2 lactose test is a commonly employed test and is very useful in determining functional lactose tolerance in vivo as compared to direct biopsy test for lactase enzyme activity. Absorption of other carbohydrates or simple sugars including sucrose and xylose also could be studied using this method.
" Normally, very little hydrogen is detectable in the breath. However, undigested lactose in the colon"

[EJ]

Another problem that can cause bad breath is your tonsils. Small particles of food can become lodged in your tonsils and cause odor.

[LisaMom]

Try cleaning your tounge..you'll be suprised at how much plaque builds up on it!! To test my theory....take your finger nail, and scrape the top of your tounge. I bet you get some white under your nail!! The tounge collects plaque just like our teeth do and it need regular cleaning. " Remember to brush your tounge regularly"...sincerely serious...Lisa