I have sudden nausea lasting less than a min. Several times during day, sometimes if suddenly active. No way I am pregnant?

Several options. Nausea, especially if associated with dizziness, can be very difficult to diagnose because so many things can cause it. Drops in blood pressure and blood sugar are two potential reasons, along with many other potential vascular problems. You should evaluate your diet and exercise programs as well and see your physician for a full workup.