Doctors love to throw out IBS a lot of time, unfortunately. IBS is usually accompanied by a rather consistent amount of diarrhea, abdominal pain, and mucus in the stool. You could have something like gastritis (which causes pain, and vomiting), or it could even be something diet related. Have you tried to cut out some things to check?
Don't fret my man, I know how scary abdominal problems can be (I've been fighting them for over 4 months straight now), but there will be a silver lined cloud somewhere down the line.