I Feel Sick Around the Guy I Like, But In a Good Way?

So there's this guy I know, he moved to my hometown three years ago and from the moment I saw him I had a crush on him. I never talked to him, we barely ever saw each other, I just thought he was the cutest guy ever. Eventually the crush went away as I never spoke to the boy. But I just started high school a few weeks ago and he's turned up in a few of my classes, and once again, the crush sprang back up the minute I saw him. He sat by me in one of my classes and we started talking for the first time ever, starting to get to  know each other. Then as the week went on he'd walk by me in the halls, tease me, and I'd catch him looking at me and smiling. A few days ago I saw him walking in the hall in front of me and I felt sick to my stomach like I was going to throw up, but in a good way, if that makes any sense. Now every time he smiles at me or talks to me my stomach hurts and I'm scared I'm going to puke, but I'm super happy at the same time. Is something wrong with me? Like is this a sign that I shouldn't be liking him, or does it mean I really like him and just have a bad case of the butterflies around him? I don't know I've never felt this way before and its confusing.