Hello, and I hope I can help you today. Nerve compression can cause numbess and burning pain, and one of the branches from your sacral spinal cord does innervate the buttock and outer portions of your genitals. Depending on your age and medical history, your symptoms can be caused by a number of conditions including problems with your back and/or spinal cord, other neurologic disorders, or infectious diseases such as shingles or even genital herpes. In order to figure out the proper treatment, you will need an examination by a physician. If you are young and sexually active, a GYN doctor would be the best person to see, if you are older or have a history of back problems I suggest you see a neurologist. They can test exactly where your decreased sensation is and figure out the particular nerve that could be affected. I hope i was able to adequately answer your question today and that my advice was helpful. Best wishes, Dr. Brown