Review Question - QID 109351

A 1-month-old girl presents with her parents to the pediatrician for a well visit. The patient has been exclusively breastfed since birth and feeds for 30 minutes 6-7 times per day, urinates 8-10 times per day, and passes 4-5 loose, “seedy” yellow stools per day. The patient sleeps for about 10 hours at night and takes 3-4 naps of 2-3 hours duration each. Her mother is concerned that the patient cries significantly more than her 2 older children. The patient cries for about 20-30 minutes up to 4 times per day usually just before feeds. The crying also seems to be worse in the early evening and the patient’s mother reports that it is difficult to console the patient. The patient’s parents have tried swaddling the patient and rocking her in their arms, but she only seems to calm down when in the infant swing. The patient’s height and weight are in the 60th and 70th percentiles, respectively, which is consistent with her growth curves. Her temperature is 97.4°F (36.3°C), blood pressure is 74/52 mmHg, pulse is 138/min, and respirations are 24/min. On physical exam, the patient appears comfortable in her mother’s arms. Her anterior fontanelle is soft and flat and her eye and ear exams are unremarkable. Her abdomen is soft, non-tender, and non-distended. She is able to track to the midline. Which of the following is the most likely diagnosis?