Why do I have morning sickness?

First of all, I am not pregnant. Absolutely no chance. None. Zilch. I am a 33 year old healthy woman. I work full time and I love my job. My job gets stressful at times, but overall I love going to work. So I think I can rule out pregnancy and stress. For the past week I have been waking up with extreme nausea. I am sick for about 2 hours- throwing up and the runs both. Then it goes away. In the evening I begin to get sick again with the same symptoms. I was driving the other day as the sun was setting and felt fine, then I began projectile vomitting and had to pull over. Then I was fine. So it comes and goes. I don't have a fever. I have extreme stomach cramping then I am fine. What gives?