My 2 cents. It has been over 2 years since the end of my treatment but I would experience swelling and moderate pain once in a while. AT the beginning, I always made appointment with Dr. to check them out, everytime they said it is just the long term side effect of the treatment and they are right. Usually, it something came overinght and cause some pain, it is NOT cancer. It is usally some sort of imflamation or infection.