Assignment Task:
Chief complaint
"The rash in his diaper area is getting worse."
History of Present Illness
Samuel is a 21-day-old African American male infant who presented to your clinic within 1 day of worsening rash on his abdomen. Samuel's mother stated that her baby seemed to be healthy since his discharge from the nursery until 1 day prior to presentation when she noticed a raised erythematous rash on Samuel's abdomen. She also noticed that her baby vomited her breast milk after three feeds. Consequently, she switched to formula, which he handled without vomiting. There were no rashes anywhere else on his body. On the morning of presentation, she noticed the rash had become fluid filled and had spread throughout the anterior diaper area including the inguinal region and upper right and left thigh. Neither the mother or the aunt tried any specific treatment for the rash, but both did notice the rash seemed to become worse over time. Both mother and aunt did not note any changes in Samuel's temperature, stool or urine quality or quantity, or appetite. In addition, there were no symptoms of increased work of breathing, cough, or lethargy. This is Samuel's first medical visit following discharge after birth. Patient's family denies any illness within their current household and visiting relatives. The patient does not attend daycare.
Question: What are the key findings and differential diagnoses list?