When i start to jerk off i get this sudden urge

OK so this has only started to happen over the last couple years (I'm in my mid-20s) but when I start watching porn and jerking off it almost never fails that I then need to take a dump. And the urge about half the time is so strong that I find myself like running to the bathroom. And no, that doesn't turn me on, but jerking off gives me that sudden urge. Almost never fails. Any other guys ever go through this?

PS- I even did ask a proctologist about this and he couldn't give me an explanation. haha