For About Two Weeks I've Had A Constant Mild Nauseous

For about two weeks I've had a constant mild nauseous feeling, but I never actually throw up. My abs involuntarily contract, about the same as if I were doing a crunch. Usually that will happen 5 or 6 times in quick succession, and then I'm okay for awhile. That repeats several times a day. Sometimes this makes me burp or I feel stuff come up in my throat. Nothing hurts and I don't think I have a fever, but it makes me think something's wrong. What do you think this is, and is what is a likely solution?