Every time i masturbate i end up with an itchy rash on my hand. it isn't contagious and goes away on its own after a week or so. what could it be?

Irritation: You may be allergic to the rubber in the dildo if you are using one. Try Hydrocortisone cream or wear non-latex glove next time. This is certainly not the usual outcome. I am more concerned about your suicidal thoughts. Have you consulted a professional or called the suicide hotline to get help? If not, i strongly urge you to do os.