The problem I'm going to talk about affects 3 people in my house. Two of them are my children. We've all seen the doctor at one time or another, and have undergone some basic tests but have yet to come up with a reliable diagnosis. Although the presentation is not the same in all of us, I believe it may be the same or similar causes.
I get an indigestion that is, best word I can find, strange. I feel lousy, sour, bloated, maybe even nauseated. I will get the most foul smelling burps you've ever encountered (like rotten eggs). I've kept food journals and such and can't pin point it to any food type or pattern. I do know if I take antacids I often get it more often then. I was tested for H. pylori and that came back negative. Doc says it's dietary, I'm not convinced.
My husband gets similar symptoms, too, just not nearly as often. I get it sometimes weekly. It will sort of "move down" into my lower GI and causes diarrhea without cramps. Actually, it feels exactly like being gassy.
My children get something similar, but they throw up. Often without much warning, and then they'll continue feeling fine. I've never tried throwing up to see if that clears me up (maybe I should, might help pinpoint this down as the same or not). It happens sometimes 1-2 times a month. They get no other symptoms except sometimes the loose stools that follow like me. I don't always smell the burps from them (I think the fact I burp keeps me from tossing lunch but not sure) but the rest seems to fit.
I've researched this on the web several times and have found nothing that sounds reasonable. I've been dealing with this at least a few years, the kids a bit over a year. It's really strange, and I'm tired of cleaning up vomit so if you have ideas, please let me know.