What Causes Black Spots On The Hip With UTI?

I had reacouring urinary tract infections, my obgyn sent me to urology last year and they done a systoscopy and urinary strecht on me I went for my yearly obgyn visit last month just for them to tell me that I still had blood in my urine which ment another trip to urology for a systoscopy, urinarytract stretch and this time they also ran dye thru my system and took a lot of x-rays, as I was walking down the hall to leave the clinic I passed the room with 2 screens in it that had my x-rays on it , I stopped and took a look at them just to see that I had a few black spots on the right lower side of my hip area which was not on the left side of the hip, I am worried and would like to know what you think about that.