What Causes Severe Leg Pain After Eating?

I experience severe leg pain after eating. This pain has been present for ~ 4 months. In March it was discovered that my creatinine level was at 8 and, after studies were conducted, it was determined my ureters were being blocked by an enlarged prostate encroaching onto my bladder (I have prostate cancer which, also at that time, was showing a PSA of 22). Nephrostomy tubes were placed and my creatinine did go down to 1.5; however, I am still experiencing the same leg pain. Is there any thought as to what could be causing this leg pain after eating?