Severe Kidney Pain

[julieinthesky]

I have what I call "Kidney attacks".  They always start out just like a period cramp in my abdomen then i can actually feel it travel around to my lower back on both sides (kidneys).  From there I begin to experience, what I can only explain as, the most severe pain I have ever felt in my life (gave birth twice).  The pain is excruciating and causes me to have to lay flat and place my arm or something under my back (kidneys).  I cry in pain for about anywhere from 5-10 minutes then it abruptly stops just like it started (unexpected and fast on set).  It used to only happen about 1 or twice a year but lately it has happened the past three months on exactly the same day.  I know that sounds weird, its weird to me, but since they started back and fall between my periods I started logging when each would occur.  I had my most recent attacks on 6/30, 7/30, 8/30 and probably tomorrow.  I was more puzzled at what they were and what was happening but since they weren't very frequent I would forget about them during any future dr visits.  But now they are literally occuring every thirty days.  Does anyone know what this could be?