Hi Lasco,
I really feel for you and i know what a little of what your going through. I experienced it to a degree at the end of high school. I worked out it was mainly due to drinking too much milk at the time. anyway the point of my message is that i've done a lot of research (btw im a med student with a Science degree so i know where to look) and i found 1 article on a 7yr old who had a breath problem. it was found that her gut was producing weird gases which she was excreting in her breath due to too many Antibiotics . She was given 4 months worth of mutaflor, a probiotic containing E.Coli, not your usual lactobacillus yoghurt based ones. After 4 months they tested the gases and she was cured. Follow-up at 7years old showed it hadn't returned. If your confident that its not an oral bacteria issue this might be worth a try. i don't think mutaflor is available in the U.S but it can be bought from Germany. Mpdela did some research when i posted about it a few months ago.
Good luck with everything