Hello Doctor Rynne, I Am A 55 Y/o White Male,

Hello Doctor Rynne, I am a 55 y/o white male, and have been prescribed Vardenafil for 4 years now. As of the last year, I have noticed the frenulum on my penis, isn't sensitive any longer. Is this something that comes with age, the medicine I take or something else? Even when I masturbate, I have to grab the base of my penis to make it feel anything. It's not very sensual doing this either. I would appreciate any help you can give me, with the sensual problem of my penis.
Missing my woody sensations