Hello. I am a 19 year old male who as been sexually active in the past and never had any problems. Recently though I was about to have sex with my girlfreind for the first time and couldnt get up. I get up when we are fooling around but as soon as we stop it goes away and I also notice that my erection is not as hard and full as it used to be. Things that may be important: I smoke a lot, exersize a lot, mastrabate at least once a day. When I mastrabate I can get it up but it is not as hard and goes away if I dont continue to stimulate it. Im only 19 its scaring the crap outta me! What can I do??