I originally learned how to masturbate when i was young, by laying on my stomach and pushing my hands into my penis . I am a 19 year old male and have trouble getting erections, or if i could get one, i cant maintain it for a long time. I recently went to my doctor and told her this, she prescribed my viagra . I tried it and it definitely did help me get an erection and maintain it for longer, but i still find myself losing it during sex. I need to know if I have done permanent damage to my penis, and, if theres a possibility of fixing the damage.