I can't get this girl out of my head and it's bringing down my grades. She seems to like me but I'm not sure. She makes weird excuses to be around me. She used to tease me about it but then stopped. Whenever I'm not around her I feel like I'm going crazy. Whenever I am around her though I fell like there's no problems in the world. Please help me either get her out of my head so I can focus or maybe tell me what I could do to see if she likes me.

How old are you? Sounds like hormones and teen attraction. You get her out of your head by focusing on other things. Are you in sports or a club of some kind at school?
Do you ever talk to her? The only way you can know if she likes you is to have conversations.

You teenagers don't have any balls to tell somebody you like them. And you think it's a shame, but it's not. Stop being a , be the man! Go tell her she looks cute and you'd like to go on a date with her, don't fool around. There's nothing bad in it.