My Fiance and I have been together for 4 years and we have been sexually active. After sex, my butt itches and it is kind of sore. We don't even do anything during sex to make it sore. She is usually on top and I am wondering if her fluids could be a result of the itching. It has been going on for several years. Usually the next day I am itching like crazy and I can never reach it. It feels like the itch is inside my rectum. We have both been tested for STD's and they came up negative. It's an itchy, burning sensation and it is very uncomfortable. Any help will be appreciated.