A 28-year-old woman presents to the emergency room complaining of ‘menstrual attacks’ with severe epigastric and periumbilical abdominal pain. Her abdominal pain does not change whether she is sitting or lying down or leaning forward. She denies fevers, chills, diarrhea, constipation, hematochezia, melena, dysuria, or hematuria. She has no skin problems. She has cut down on her carbohydrates to lose weight as she prepares for a bariatric surgery. Her work as an accountant is also stressful due to tax preparation season. She is not taking any medications now. She never had these symptoms before puberty. She is not sexually active. This is the fourth visit to the emergency room for the same complaint over the last calendar year. She feels normal between the attacks of abdominal pain. She had undergone CT scan of the abdomen, endoscopy, and colonoscopy. When asked about the results, she reports, ‘they said all tests came negative. They couldn’t find anything’. A diagnostic laparoscopy also did not reveal any pathology. She noticed her urine changing in color with exposure to air. Your physical examination is significant for the absence of abdominal tenderness. The deep tendon reflexes are hypoactive. Pelvic examination is normal. Her skin examination is normal. What is the most likely diagnosis in this patient?
