You should tell an adult that you trust what's going on. This might be a parent or another family member. This could also be a teacher or counselor at school or maybe a coach or mentor.
It can be very scary to open up to others about our thoughts and feelings you might think about taking a moment to write things out. This can help you to keep your thoughts organized so that you are really able to clearly present your concerns.
The yourlifeyourvoice website has some great articles and journal pages that you might find helpful. Take a moment to check it out.