I've been twitching for a little bit now. Maybe a few years. I'm 13 almost 14. Sometimes I bob my head forward. This has been on and off and my family and kids at school has asked me about it. I've been told to stop but its hard to. I can stop myself if I want but it is hard to refrain. Should I be concerned? Do any of you know why I do this? I need help, thanks.