A 29-year-old woman attends the GP requesting investigation for chronic pelvic pain. She has had the pain for 18 months. It is non-cyclical, constant, and affects her daily life. She has had a normal pelvic examination, normal ultrasound, and negative STI screen. A laparoscopy 6 months ago was normal with no endometriosis. She remains distressed by the pain. Which is the single most appropriate management approach?