Need an opinion..

Hi, I'm an 18 year old male and recently have thought I've been urinating more often.. I've also had a weird kind of feeling on the left side of my abdomen.. I don't really know for sure where its at, doesn't hurt or anything just feels kind of weird, like tingly.. There is no pain or discomfort urinating it just seems like I'm going more often and sometimes have a weaker stream.. I have also had a lot of pain in my lower back, I was wondering if anybody might have any idea whats going on or if its not anything to worry about.. Thanks!