Out of the blue vomiting?

I started feeling a little ill toward the end of work yesterday and shrugged it off. I felt fine until I got home and just pretty much projectile vomited five times back to back. I ate something and felt fine. Today I got off work again and went to grab a bite to eat only to throw it right back up within minutes. Any idea as to what could be wrong with me? I rarely ever get sick and it's an even rarer occasion I vomit, but this episode has actually made my throat so sore after that I can't speak.