WHAT THE **** IS GOING on?!?!?!?!?

i like this guy, I thought he liked me but we just had spring break and over it he wouldnt talk to me and he went away whenever i said hi to him on AIM. Then we got back and he acted like nothing happened and now we still talk a lot during cl but not in the hallways like we used to (before spring break we started talking a lot after almost every period and we shared ipods and stuff and he was really nice to me) I see him look at me every now and then. sometimes he talks to me in cl on his own, mostly he never says hi but he will talk a lot and walk with me when i say hi to him first but to all of his other friends that are girls he will willingly say hi and walk and talk with them. He is also always leaving all these weird messages on AIM on the thing where you type your status but only on the sn i have and as far as i am concerened there is no other girl WTF is goin on, what could i have done to turn him away? And how can i show him i like him or figure out if he likes me?!?!?