I can't believe he would keep doing this! Please help!?

I really like this guy and he's in my form and I see him at break but whenever we talk on facebook it's always very short and he's always like gtg now cya and i'm like :/ if he liked me he would say more than that.. Also in class he was always looking at me which he does less often but now he compliments me lots... Sometimes I feel he must definitely like me sometimes I'm not so sure :S I don't know how I can tell if he likes me or how to get the message across that I like him? Please help - thanks <3