I'm really scared of it being something serious. I'm eighteen-years-old. All of this pain just started today. I came home from school, and sat for about a few hours just doing my homework. When I tried to stand up, my navel started having sharp pains, and it was pretty intense to me. But, after a little later, still standing up, it stopped hurting. But the apin does come back when I sit back down, and stand up a little later. When I stood and urinated, it only hurted a bit. No blood in stools. Urinating doesn't hurt when I'm sitting. When I bend back a little, it hurts. It only hurts a little when a bend forward.

Please, I need some insight on this.