What Causes A Delayed Menstrual Period And Back Pain?

I am a typical 13 year old female. I play sports and weigh 140llbs. I take good care of myself and keep track of my menstral cycle. As of now, I am 5 days late. I have never had sex, but I'm still worried. I have also obtained a bladder infection and it is quite painful. My back is sore and it is almost impossible to urinate. I was wondering if the two might be conected.