Around late December 2015 my sex drive vanished completely and would rarely pop back up on very rare days, as a consequence I have trouble getting erect due to the lack of arousal. To make matters worse my scrotum is always tight now and does not hang as low as it used to, it is also experiencing itching and irritation with no visible sores or bumps. What is causing this? I have already been tested for stds and HIV last week and it all came up negative. I am a 21 year old male.