Demons. A serious question.?

Ive been being haunted by a demon. I believe it started because a while ago i was into Magic and me and my friend were contacting the dead... But whatever caused it idk. ive seen things moved in my room, ive seen and heard some figure of sorts and its followed me from where ive lived over my life so far. I need to get rid of it, i havent slept in 5 days... But im trying to avoid Magic, for fear of accidentally making it worse. At night i hear it breathing next to me and its been scratching my back. Im only a teenager, not some hyper jackass thats imagining things. I have scars from the scratches. What do i do????? Ive been possessed before, for 4 days... Please help me... i dont want my parents to know though so id rather not have to go to people for help in person. Please help me