I also experienced kidney pain after starting an oregano cleanse. I bought the potent oil caps and took 2 in the AM and 2 in the PM, I actually experienced a die-off within the first 2 days. I had a positive candida ELISA and I am on diflucan which is not strong enough so I added the oregano. 3 days into the oregano I started getting stomach pain that within 2 days became sharp pains in my kidneys and by 5pm I was throwing up and thought my appendix was going to burst. I went to the ER and they found that I had small stones in my left kidney and a large one in my right kidney and they had come out of the kidney into the ureter. So evidently the oregano had somehow dislodged and began to flush out these stones. So now I am taking magnesium and oregano and lots of water and painkillers to see what happens.