The cases get harder!
These images are from children under the age of 5 with symmetric sudden eruptions of raised lesions, mostly on the cheeks, buttocks, and extensor surfaces of forearms and legs. The lesions were preceded by an upper respiratory or gastrointestinal illness. The lesions do not go away and last for weeks. Itchiness varies. Some patients have lymphadenopathy; some have elevated liver function enzymes. The lesions usually spontaneously resolve after weeks.
Challenge: What's your diagnosis?
First image is in the public domain. Other three images shown under Fair Use.