My back is hurting

I am on day two of the Master-Cleanse and although I am not hungry or tired, my lower back is hurting. like around my kidney area. I know that I should'nt be concerned with it as it may be a symptom of toxins being stirred up in my body. It's quite unsettling and I was wondering is there anything that I can do to relieve the pain? I know Tylonol is not an option.