mrcem2-1348

A 25-year-old woman comes to the emergency department with severe and continuous nausea and vomiting. She is currently 8 weeks pregnant. She is struggling to retain any food and has experienced slight weight loss over the past two weeks. Her vital signs are as follows: heart rate 103 beats per minute, respiratory rate 14 breaths per minute, blood pressure 113/70 mmHg. Her abdomen is soft and not tender, and a urine dipstick test shows 3+ ketones.
What is the MOST likely diagnosis?