I m a 50 yr old male, I m been sexually active all my life. Over the past 4-5 months, I started to find it hard to maintain and keep my erection even though my excitement is extremely high. I still do ejaculate, however, I do so without FULL erection!!!! It s about 80% erected. In the past, after ejaculation it was never difficult to reach erection within 30-40 minutes, unfortunately now, it takes several hours. Kindly advise.