I Consumed A Very Light Meal Of Chinese Food Today,

I consumed a very light meal of Chinese food today, and it was all I had consumed. During the day I had drank Diet Mountain Dew. Recently as an hour ago I vomited quite a lot. To relax Prior to the vomiting I had consumed a couple of beers. Not the best diet I know for a day right? I feel that whenever I drink Diet Dr. Pepper or Diet MTN Dew I have A high chance of vomiting. The Chinese food is always good, and the beer of choice never induced vomiting. So, what can be in diet MTN Dew that could induce such aggressive vomiting?