hello sir i have a problem with my penis, for a bout 2 weeks now i am not able to have proper erections, mainly when a girl was on op of me naked ( this happened 3 times with two different girls). of ten id have to actually jerk myself in order to get the erction and most of time it would not work or not be erect to its fullest. i feel like my penis in constantly shrinked, what can i do to get back to a normal sex life,i m 18 years of age, exercise often and eat well, i dont smoke regularly.