I have been married for 3 years, but since starting i am not able to maintain a good hardon while sex. While starting sex i get a very good hardon but When i insert penis in my wife i keep doing for 5 minutes after that if i try to change position or sometimes automatically penis becomes small and doesn't matter how hard i try, it barely get hard erect again. It becomes medium erect. What shall i do? From past 3 days i have started taking ashwagandha, any other suggestions?