Urges can be such a hard thing to deal with. However, there can be so many helpful things to do for prevention of self harm. It seems like such an easy thing to do but is actually extremly hard. simple things like taking a bath, writing, reading, talking to someone i mean there are so many options its endless. Even something as simple as talking to someone on blah or listening to music. I love meditation because its able to calm me down and have a different perspective on the situation im going through. In my rehab a lot of people would take sharpies and draw on themselves. I would reccomend you to see or tell someone about the voices in your head so things will be easier for you.Here are some websites for alternatives.
http://studentsagainstdepression.org/get-support/check-suicide-and-self-harm/coping-with-self-harming-urges/http://discussingdissociation.com/2008/12/31/25-ways-to-avoid-self-injury-and-prevent-self-harm/One last thing i want to say is that i understand how difficult it can be when you feel like you cannt trust anyone. I think it would really let go of the stress your dealing with if you could talk to someone. I know that everyone on blah therapy would be non judgemental and would support you through your struggles. A family member, therapist, close friend, or even someone on here. I hope this helps and you can recover:)