I am a 73 year old fairly healthy and active woman. I have experienced back pain, tail bone pain and leg pain in the past. Now I am experiencing hard buning pain in ctr. of left buttock and down the back of same thigh.Pain has also developed in the groin area of both legs, worse on the right. It feels as though panties are strangling the tops of my legs, burning and pinching, but having tried going commando the panties are not the issue.My pain is always present when sitting or lying down, not so much when upright. Ice packs seem to bring the only relief. These symptoms have been present for over two years, despite having lumbar MRI s (no visible cause) an EMG of the prudendal nerve which did show a possible delayed nerve function. I have also been tested for HLA B27 and am positive. this Can cause ANkylosing Spondylitis. I have been to orthopedic dr s, neurologists, and now to pain mgmt.at Beth Israel Deaconess in Brookline, MA. I had guided shot in the left buttox (prudendal nerve) and another in the piriformis muscle. Neither helped at all. I am 5 4 and weigh 134 lbs, so being obese is not the issue. HELP.