Is it one sided or in the middle? I ask because it sounds like of like what I feel when I have had cysts on my ovaries. Last time I had the issue with it getting worse when I went to the bathroom but it just happened to be the way the bladder pushed into the cyst when it was emptying.
Not sure if this is what is happening to you but I am not sure I would mess around with it. Might want to see a doctor as soon as possible and if it gets any worse an ER trip might be needed