Why do people automatically doubt my honestness?

Lots of people call me a liar when they barely know me. Why?

I talk to people at school and on streets, but most gawk and walk away. Teachers always think it was me, when something goes wrong, even when I know it wasn’t. They say I don’t do my homework when I do. My parents are against me. I can not drive at night and I have to come straight home from school. They think I’m Goth or something. Facebook people post crap on my page bout lying and exaggerating. Why is this happening to me.