i have trouble achieving and maintaining an erection for sex. i have never been able to have sex until recently - my doctor said it was anxiety and prescribed me viagra to give me a kick start. didn't think i'd have any problems after i'd had some good sexual experiences, but i still do. i still need the viagra, and sometimes even when i do take it my erection dies after about ten minutes of activity anyway. this has gone on as long as i can remember, i have little hope for my sex life. he said come back if you still have problems, but is there any point? isn't he just going to give me more viagra? what sort of action should i expect my doctor to take? ps, i can keep an erection fine when i masturbate