I am a 42 years old unmarried. I am unable to maintain erection continuously even for 10 seconds even when I take any pills like Tadalafil 20mg, etc.. i.e. No erection pills are effective and of course, since from my very first time of masturbation time itself. I have been masturbating once a day regularly from the age of 16 years and in somedays even twice. Otherwise, I don't have any bad habits even smoking, etc. nor had any significant medical history. But, I feel always tired of doing outside works like walking and l could not lift even a 5 kgs weight  even for a while. Moreover, my semon overflows at all times even in the bed at night and and while urinating. Recently I came to know my Sperm count was just 12 millions with half an amount of motility. Please suggest how can I maintain satisfactory erection in my sexual life and prescribe me suitable Doctors to overcome this problem.