Lower Back Pain on Liquid Diet?

I am on day 12 of my liquid diet--my RNY is scheduled for Monday (today is Friday) and I have had horrible lower back pain that is radiating into my legs. I had this pain once before when I was first on Atkins years ago. Could this be my kidneys? Toxins being eliminated from my system? I also have diarrhea. I can't take ibuprophen. I am trying to drink a ton of water to flush my kidneys. Any ideas?

I am on day 10 of my liquid diet.. miserable isn't it...as far as the pain I have had none just the typical back pain I have had because of the excess weight, but I have diarrhea constantly, I don't don't know where is comes from.. I have it so often I now have to put on tucks pain relief cream my dad uses on his hemorrhoids.. This better be all worth it...

It sounds like it could be your gall bladder. I had surgery 4-02-08, experienced back pain, had a gall bladder ultrasound and they found gall stones. Because my symptoms showed up so soon after my surgery, my Doc said they had to be pre-existing. When I went online to read the symptoms, I realized I've probably had stones for about four years. I swore it was my kidneys too. I insisted on a urine even after a CAT scan (before the ultrasound). I did South Beach and Weigh****chers off and on for about ten years. I'm not surprised I have stones. I read it's hereditary too. Let me know how you turn out. It sounds like your pain is worse than mine. Hang in there.