It sounds a lot like OCD.. I would go get diagnosed for sure though because I'm not a doctor, I just suffer from it. The thoughts are the worst part by far. I would go to a therapist, maybe you have one at school or in your town. I just saw a school therapist and I took an OCD screening test type thing and I was diagnosed and referred to a psychiatrist for possible medication. Just know even if you have the medication you don't have to take it. Also online you can find OCD work books which can help you cope with your symptoms. I hope you can find some peace in your head.