What causes nausea?

I have been nauseated ALL day long. I have tried gas x, tums, rolaids, and now just ate 5 whole grain crackers. The crackes seem to be helping but Im just wondering what causes the nausea?

It started yesterday after I ate pretzels and peanut butter and hasn't gone away. Should I call my surgeon?

maybe you just got a 24 hr bug.

Make sure you're getting all your liquids; that can cause nausea.