I've had similar symptoms and have considered that an h. pylori infection has returned.
hey
nausea is a symptom of ibs as well as the following
painful constipation
painful constpaton and diarrhea together with abdominal pain
diarrhea
swelling {distension}of the stomach with wind{gas}
unprecdictable erratic bowel movements varying from day to day
dyspepsia{indigestion which could lead to nausea}
have u been to your doc there are meds u can take for constant nausea
hpoe that helps a little