What does it mean when a guy does this?

[Jessie Sanchez]

Everyone knows him, but me. Every time I see him, he'll look at me or won't look at me. him and I were walking in the hallway( he was w/ his friends) and my guy friend called my name, so I ran to him and he gave me a mean look. I added him on Facebook and he accepted my friend request in less than a minute. Literally.(I have tons of mutual friends with him, but I don't talk to them anymore)he goes in my personal space in the hallway. He was acting weird and when he saw me, he tried to act normal. And he kept turning around and giving me mean looks. I was in the hallway & I saw him and he moved closer to me w/out touching me.He kept staring at me and he(his friends) were near my locker and he said that someone smelled good( it was me). I got my hair straightened and when I saw him, he gave me a happy look. Now when he sees me, he'll either stare and look away or go near me.