A 20-yeаr-оld wоmаn presents tо the student heаlth office with a 3-month history of fatigue. She feels exhausted and has not been able to engage in her studies. She has been going out with friends to sports bars multiple times per week and says that she eats and drinks a lot on those occasions. When she gets drunk, she cannot help herself from eating huge plates of fried foods. She then vomits overnight because she is intoxicated. She has no significant medical history and is up to date on her vaccinations. Her temperature is 98.7°F (37°C), blood pressure is 124/72 mmHg, pulse is 84/min, respirations are 12/min, and BMI is 24.6 kg/m^2. The findings shown in her photo were seen. Which of the following is the most likely cause of this patient's symptoms?