Why do I have an strong urge to contact guy who rejected 8 months ago

He rejected me countless times over the course of 4 weeks and called me a stalker. I eventually left him alone and he still has me blocked. I still can't stop thinking about him but the after a while the urge to contact him went away because I knew he would just be nasty to me and I didn't want to contact him if he was going to be nasty. He never used to be nasty to me until I wouldn't leave him alone. He still has me blocked on facebook. I know his number off by heart.

8 months later and his sister and cousin kept teasing me about him so I blocked them last week, hoping it would help me get him out of my head but I'm starting to think it might have been a mistake because I am now thinking of him more than ever.

When I sleep I don't normally have dreams about him. I've dreamt about him about 4 times, but this week all my dreams have been about him. I slept for only 3 hours last night because I had a dream that was so realistic. I woke up as we kissed and couldn't get back to sleep

I try taking my mind off him with telly, playing the guitar, computer games and internet stuff but he's always at the front of my mind. I've had crushes before but this one feels like the worst and longest. Normally it doesn't take long for me to get a crush on someone else but no matter who I fantasies about the fantasy always comes back to him. I can't unblock his sister or cousin because they would start getting nosy and saying " why did you block me" and I'd end up giving them something else to laugh about but since blocking them my urge to contact him is getting stronger and stronger.

I've seen him 3 times in the past two months and we didn't speak a word to each other but I've noticed he won't stop staring at me. The first time his eyes went wide and he smiled at me but I ignored him cos I'm too scared to talk to him in case I made him uncomfortable. The second and third time he still kept staring at me but he had sad puppy dog eyes. Ever since I met him he has always stared at me and I told him when I asked him out that one of the main reason I thought he liked me back was cos he kept staring at me so I would of thought that he'd make an extra effort from now on not to stare at me. When he stares at me he's either smiling or pulling the puppy dog face, and he always goes bright red when I catch him.

I keep thinking what if he's always like me but is too scared of what people might think, because I'm not very popular and people make fun of me, so if we got together they'd make fun of him too.

I don't know what to do I've tried everything but this feeling won't go away. 8 months is way too long and I should be over it by now. Its not as if I need closure or something cos I asked him out and I got my answer, I should of been over him a long time ago but I just want to text him. I'm not going to but I have a strong urge to and it is driving me insane. I've never been this fixated on anyone before and I have had crushes on people who were my best friends in the past. He's nothing to me but he feels like everything.

Why can't I stop thinking about him? Do I need counselling?