I'm sorry you're feeling so bad. Do you have a therapist? It sounds like it would be good for you to have someone like a therapist to talk to, and to teach you coping skills for the times when that urge hits. I s/h too, but it's been 5 months now, I've learned some very helpful coping skills. (DBT)

Is there anything you can do to distract yourself? Maybe you could try making a list (preferrably when you're feeling okay) of things you can do instead of s/h. Simple things, nothing major. Things like putting on some music and getting out a coloring book and some crayons. Baking something works really well for me. I actually have a very long list of alternatives to s/h. That way, when I get to that point, I don't have to think, I can just look at my list and pick something, and if that doesn't work, I just pick something else.