Confused?!?

Basically there's this guy, who i was very good friends with last year. He started talking to me on facebook, near enough every night and smiling/ looking at me in class. His friends also started looking at me, and he kept walking past where I hung out at break. He also kept liking my facebook status', was that just being friendly or something more? However, this year he has changed and seems to really hate me/ be jealous of me in class. He started sitting with his back to me and ignoring me, br I had no idea why. I think he also used to complain about me to his friends. A few months ago it was like he was back to his old self, sitting close to me in class, giving me direct eye contact, talking to me on favebook every day and liked all my status' and my profile picture. And at this time a different guy told me he liked me, and I told him and he told me to reject this guy/ tell him to go away. But now I feel like he's gone back to being mardy with me. I really dont understand him. Anyone explain his behaviour?

Basically there's this guy, who i was very good friends with last year. He started talking to me on facebook, near enough every night and smiling/ looking at me in class. His friends also started looking at me, and he kept walking past where I hung out at break. He also kept liking my facebook status', was that just being friendly or something more? However, this year he has changed and seems to really hate me/ be jealous of me in class. He started sitting with his back to me and ignoring me, br I had no idea why. I think he also used to complain about me to his friends. A few months ago it was like he was back to his old self, sitting close to me in class, giving me direct eye contact, talking to me on favebook every day and liked all my status' and my profile picture. And at this time a different guy told me he liked me, and I told him and he told me to reject this guy/ tell him to go away. But now I feel like he's gone back to being mardy with me. I really dont understand him. Anyone explain his behaviour?