Throwing up on an empty stomach.

I didn't eat nothing but a bag of chips at work. I eat after work and never had to puke , I started to feel sick and threw up a little. I went to the mall for a massage and I threw up again and got over heated. Why is this happening. My period is due July 3rd. I've been cramping since the 16th my fertile days was on 14-16 and I've been super tired.