Random depressing mood.

Yeah, so I've just become really randomly depressed. (Again.) This happens a lot and I really don't know why, it's just one moment I'm listening to music, quite happy, drawing etc, then I have this little voice inside of me telling me I'm gonna fail all my exams, die alone cos nobody loves me, that I'm an ugly fuck, and that the world would be better off without me. I really don't know what's going on, and I can't tell my friends or family, they'd think I'm mad, which I probably am. I dunno, I'll just keep drawing or something. Maybe if I turn my music up loud enough I won't be able to hear anything. But then I'll get shouted at for having my music too loud. Again, I dunno, just thought I had to tell someone. :(