Getting worse and better

I have found myself eating a lot more than I normally do, but when I do eat, I end up eating so much till I get sick. I don't know what is happening, but I keep telling myself I just need to eat, but I always get really sick. I have had a lot of urges to throw up, but I can't so I just feel horrible. 

My PE class is way too hard on my body because of how horribly I am treating it, and I need to run a mile on Monday and I could not be more scared than I am. 

I don't know what to do.