Erectyle Dysfunction. Health should do?

Hi.. My case: I'm a 27 year old unmarried man. I am suffering from erectyle dysfunction. I am not able to hold a full erection for not more than 30 seconds before I get semi erect. I figured out that there can be many possible reasons for this (google).But my case i'm pretty sure it is related to nerves. I over masturbate and masturbate for very long intervals (at times even when am not erect) and i suspect I have done some damage to my penile nerves. I am able to attain full erection though just that I have to give like a week of recovery time for my penis. I also have light smoking habbit (planning to quit) which can affect nerves. My questions to you: 1. Is there a treatment where I can fully recover my penile nerves which inturn should help me with frequent erections and holding an erection for longer? 2. Do u think i have to visit a doctor for this or any over the counter medicines which can help with nerve health should do? Please help. Really appreciate your time!