HELP. I think I love a guy, but I'm 15. Please read this and help me, I just need advice!?

I'm a 15, and recently (namely, last week) I suddenly noticed this guy at my school. I've known him since 4th grade, but I never noticed him really until now. I immediatley went absolutely crazy for him, stopped liking the same guy I've had a crush on for 3 YEARS, and now I'm absolutely infatuated with this other guy. The thing is, he is not especially handsome, and I'm not trying to be mean, but I'm much better looking than him.. there's just something about him that draws me in like heroin.I NEED to at least try things with him. I think he likes me too, but we are both shy, and I don't know what to do! HELP!?