Can Someone tell me what type of mental disorder i may have. I think i may need a test.?

I have suicidal thoughts occasionally. I have had a mental breakdown before. I get paranoid when i download songs. I cant just download one when i want it. I have to download the full cd. I start screaming at people when they ask the same question over and over. Before me and my mom left my step father I would occasionally discuss with someone close to me ways we could kill him and get rid of the body. I have had the same thought over and over. I have had the thoughts with other people also. My cousin had called me Obsessive Compulsive before. I think it's something worse than that though. Heavy Metal music such as Slipknot, Korn, Avenged Sevenfold, and Bullet For My Valentine cures my saddest moments when softer songs can make me sad. I usually feel violent urges and have a sickening obsession with death. The smallest thing can make me want to die. I have taken a brier thorn and jabbed it half way through my lip. Does anyone know what may be wrong with my mind. Should I have it checked out, for future reference?