What Causes Stomach Pain,diarrhea And Vomiting?

I'm skipping all of my personal health info because I believe that I have just a basic question: yesterday morning, my stomach started to feel a bit queasy, and that feeling lasted through the afternoon. Later that evening, I started forcefully vomiting, even projective vomiting, and that has been accompanied by watery diarrhea (and having to run to the bathroom every 20 minutes or so.). Today, it has not cleared up, except that I am not vomiting; but then again, I have not eaten anything all day, only drinking ginger ale. I did have an instance where I did vomit, but since my stomach is empty, it has only been the one time. I am, and have been all day, weak, and sore, especially my face and eyes. I had initially contributed this to food poisoning, except that my girlfriends son has also been vomiting (without the diarrhea, though), and we didn't eat the same things. The other possibility is just flu (my temp is 99.6), but there were really no signs before I became ill. What would your opinion be?