Hi,
Welcome to HealingWell!
You won't find too many people with IBS vomitting. Nausea and pain do occur, but vomitting is definitely not "common" - especially a handful of times a month. It happens to a few people when the pain and/or bloating gets really bad.
Have you spoken to your doc about
your symptoms? Are you on any meds that have nausea and/or vomitting as a side effect?
My sister had radiation treatment for a brain tumor, but she didn't (hasn't) experience any of your symptoms. She does, however, take Calcium daily. Calcium will help with your bowels, but I'm not sure it will do anything for the nausea. You might consider talking to your doc and eating a low fat diet in the meantime. You can also try tea for the nausea. Ginger seems to do wonders.
Hopefully someone else will be along shorty who can give better tips.
Take care!