A 5-year-old boy presents with generalized colicky abdominal pain, pain in his right ankle, and a rash over both lower limbs for 2 days, along with fever for 1 week. No other symptoms are present. On close questioning, his mother recalls that he had a sore throat around 2 weeks ago.

His medical history is unremarkable. His mother gave him oral acetaminophen (paracetamol) for the fever. He has not been on any other medications recently. There is no history of recent vaccination. He has no known allergies. His family history is also unremarkable. He is on a normal adult diet.