Self-hurting, Hitting My Head Against The Wall. Why Am I Like This?

i m a teenager and i recently relized that when i hit my head agsinst the wall or claw at myself or bit myself that i am self hurting i thought because i m not cutting that it didn t count but now i m more courious i sometimes feel like i m two diffrent people like there the bully and the sweet girl i feel like i m pmsing constently i used to be better at hding my feelings but i seam to have lost that skill i m wondering if there is something eles wrong with me and why i feel like this i m trying to stop the self hurt but when i try the feeling just gets stronger i m paralized because if i move i will hurt myself when that state comes the walls around me call to me all i see is a way to hurt myself my nailes long to get deep in my skin and my teeth only want to punctur into my flesh am i just exagerating and if not please i could use ur help thanks