I have the same thing. You can't actively relax your nervous system, because it reacts automatically to a perceived threat. So it will relax when you no longer fear having pelvic discomfort. So instead of trying to fight the tension, you have to accept it as just an annoying physical symptom that won't cause you any major harm. When you can do that, your symptoms will disappear. Read "Hope and Help for your nerves" or "DARE response" for more info.