Erectile dysfunction. 15 mints daily.

Sir,i m 25 yrs suffering problem of ed i use to watch porn and masturbate after some time i lost my normal erection 4 to 5 yrs back when i try to make love with my partner ,i have consult sexologist he gave me the medicine for around 8 month ..for maintaining blood flow, increasing sperm count, and for muscle weakness. ..now that treatment is over 10 days ago i was happy my erection was there every morning and after just little imagination i was able to get erect but suddenly 7th day onwards problem start occurring now i have to imagine or concentration more like its not pleasure its tension and then erection occurs but at the end of climax for while i went to my doctor he check me again my blood flow was 96%..sperm count and testestoran level was good muscle also strong ..then why i m facing sudden problem i m not drinking alcohol, not smoking, not fat ,and even run for 15 mints daily .