I agree, stress can definitely cause this. In my own experience ( I live in California and I am 23 now) I was always going out with friends and drinking, (i admit) I did illegal drugs which was ecstasy and then I got married to a guy who was in military and a day before he left on a deployment he admitted that he cheated on me with basically one of my friends (it was a little more complicated than that) so I had a really bad Depression and I started drinking wine every day, about two bottle sfor a bout three weeks and I would often get sick from it. Also at that time all I could afford was eating at McDonalds 99 cent menu and this is when the problem started.
So I think that me drinking wine (which often has mold in it, especially cheap wine that I drank) eating bad food, being really stressed out, all of these have contributed to this problem.
After everything I have tried, I really think that what starts this thing is dysbiosis and then, depending on what part of the intestines is affected (because it is at least 26 ft long) it causes either inflammation or some other kind of gasto-intestinal disease that allows toxins leak into the rest of the body.
Bad breath can be caused by the stomach, some people have chronic halitosis which is linked to the stomach, but in our case I think it is something more that that.
Ugh, just makes me mad that some people drink all the time and eat crappy food and never have this problem.
Sorry, this message is a little "all over the place" I hope someone can make sence of it.