How do i tell a guy i care to much about and i wanna be around him where ever he goes?

There this guy in my cl and I think he still know that i still like him and it seems like he diggin me too but i also care about him alot and when he leaves i get sad because it feels like i cant be without him. Like there are times when he didnt come to school like today and i was feeling sad like i was crying inside because when he be at school i feel good and he always put a smile on my face and hes a funny person. Last year in the very begining, i was at another school for one semester and i thought i neva gonna see him no more and i missed him sooooo much that i wouldnt eat for two days and i felt sick in the stomach like i wanna throw up. I neva felt like that when i like someone and i had to come back to this year because i felt like i cant live without him. And When ever i'm around him i feel very very nervous that i be shaking but i be excited. He flirts with me and he stares at me. He would flirt with me one day and the next he would not talk but stare in my eyes.