Search Results: getting stalked

I'm going to start with a quick summary for those who don't want to read a lot because I need all the advice I can get...
-he liked me, I didn't reciprocate feelings
-it's been three years, I'm now 18, still in "high school/secondary school" and he still likes me or so I assume, since he follows me everywhere!
So for anyone who doesn't want the details, you can post your advice now.
Details:
I started this school 3 years ago and i was in his classes. I noticed he was kind of an outcast and got bullied. Bullying him was commonplace it seemed but it was never physical, usually verbal. I was never rude to him and if he spoke to me I would talk to him like anyone else.
One day my friend refused to sit on a chair after he sat on it. He could hear that she didn't want to sit on his seat and offered to get her a new chair. That is when I jumped in and told him not to and I shouted at my friend for being so rude. I forced her into the chair lol, she felt bad after she new he heard her. ANYWAY, I THINK THIS ACT OF KINDNESS IS WHAT COULD HAVE TRIGGERED HIS CRUSH, but obviously I don't know that for a fact. All I know is everything got weird from here.
The first time I found out he liked me was when my friend told me. I honestly thought it was cute and nice. But then she told me that he said he liked the way I walked? I don't really understand that? Explain if you know what that connotes please or if it's even a normal compliment to give. This all occurred within the first few months. I eventually told him I don't like him back because I don't want to waste his time obviously, but I did it in a nice way. He backed off for like a week. It's been 3 years and he follows me everywhere. My friends and people around me find it uncomfortable as do I. Recently it's been getting worse, and he's not in any of my classes, he is on the other side of the school. I didn't care before because it never affected me but its upsetting me and I don't