I'm not an expert on SI. I once gave the advice to try holding ice cubes but someone got mad. The idea is to replace a non harmful way to produce the same endorphin release -pain releases endorphins and holding the ice hurts. Do you know what stressors are triggering these urges?? Do you have a friend or family member who could help you? You've been doing so well, so please hang in there and resist. You could try some rigorous exercise or type out all your frustrations. I hope something I said helps or a least knowing I care. Be safe and take slow deep breaths.