mrcem2-1160

A 7 year old boy is brought to the emergency department by his father complaining of stomach pain. The boy has had a sore throat for 2-3 days before the stomach pain began. The patient has normal vital signs and is able to provide a clear history. During the examination, you observe a rash on his legs that consists of small raised red-purple spots that do not fade when pressure is applied. His abdomen is soft with no signs of guarding or palpable organ enlargement.

What is the most probable diagnosis?