Advice please!!!! -.-

I'm getting worried, I'm a few days late for my period & I'm not feeling like myself. I have had all sorts of stomach cramps, headaches, the need to vomit but haven't, I'm getting turned off most foods even if someone just says the name of it. I don't even have to smell it or see it. I did a test and it came back negative! I don't get any of this when I'm about to get my period the most I will get is a little cramp that will last for a couple of minutes and go away! I have been feeling like this for about a week now. I'm just worried and im not even dating the guy I'm having intercourse with. We're just seeing eachother. I was just wondering what everyone else's opinions are as I'm only 16 -.-