What is wrong with me?

About a week ago I started having weird pains in my stomach, but thought nothing of it. Then last Thursday, sorry if it's gross, I had diarrhea. Then I started to feel really nauseous and I puked a few times. I stayed in bed the next few days, still having lots of diarrhea. I haven't had an appetite either. I've just been eating bits and bobs like soup and fruit and yogurt and Ginger ale and Gatorade. I'm also very tired all the time. Also, there's no chance of it being pregnancy because I have my period right now and I'm not ually active with . I feel a little bit better today, but the diarrhea just won't stop. This is the fourth day of it. What is wrong with me? And I'm in 17, if that makes any difference. Thanks.