Weight loss and dizziness in a 29-year-old man

History of Present Illness

A 29-year-old man comes to the office because he has had weight loss, lethargy, and postural dizziness for the past 2 months. He says his symptoms began just after surgery to repair a diaphragmatic hernia caused by a stab wound to the chest 6 months ago. He first went to the emergency department 3 weeks after surgery because of sharp right-sided chest pain. At that time, CT scan of the chest was obtained to rule out pulmonary embolism, which was suspected because he was found to have low blood pressure along with his chest pain. No evidence of pulmonary embolism was noted on CT scan. He was discharged home on an antiemetic and acetaminophen. Today he says that, since the operation, he has had gradually worsening lethargy, morning nausea with occasional vomiting, and generalized abdominal pain. He feels very dizzy when he stands up and has lost 12 kg in the last 2 months.