Im a 21 year old male and remember having this problem since being a teen. Maybe a couple times a month I get this sharp pain near my belly button randomly when I try to stand up straight or lean back, I can't even stand up straight I have to hunch over the pain is so bad. It feels like there's a string from my belly button to the tip of my penis. It also hurts a little to pee when these episodes happen. It never seems to last more then 30 minutes, I always end up laying down rubbing my stomach and it ends up going away and I can stand up straight again. I currently work at UPS and I noticed more it happens after a hard day at work so I'm thinking it has to be some sort of abdominal strain? I found a previous thread from a year ago of people explaining what I'm talking about dead on. 

https://www.steadyhealth.com/topics/sharp-pulling-pain-in-bellybutton