Hi there ~ Masturbation is a natural process. However overdoing anything is not good. You should find better ways to deal with stress and to find ways of coping with anxiety as well as feeling good about yourself. Elevating your self esteem and confidence by channeling your energies in a positive direction would be a good way to start. Back pain usually comes down when you reduce masturbating as much as you are. If it still persists please consult an orthopedician. It would be good to do yoga and regular physical exercise to relieve your stress, depression and back pain. However you should take the advise of an instructor to be able to do so. I hope you find a psychologist to talk to about your feelings. It is helpful to vent your thoughts and feelings. I hope this helps. Take care and have a good day !