V.T.
Don't think you're prego. It sounds very much like mild food poisoning. Or, I get what I call my "random stomach attacks" like this all the time. Every 3-6 months or so I'll get random nausea and vomiting; I'll do it and then be fine. No other symptoms, comes on suddenly and is gone suddenly, no consistency as to why it happens. If you started waking up every morning, or multiple mornings with these symptoms, then maybe suspect something like morning sickness. But 1x, I wouldn't think twice about it.