Hello, a close of friend of mine had his kidney stones removed a few years ago. However, afterwards the scarring on his kidneys that was left behind, the kidney became infected. Cancer tests done on it showed a tumor, however, it went away after strong antibiotics. They said the kidney pain he recieved was because his kidney swelled up in defense of the cancer. For a while he did not get the pain; however, now he gets the kidney pain again. Why is this happening/ what does it mean?