A 4-year-old child presents to the clinic for evaluation of a fever, headache, generalized malaise, and decreased appetite that began 2 days earlier. He has now developed a generalized pruritic rash all over his body. Which of the following is the most likely diagnosis?

Chickenpox (varicella) - Prodrome - fever, malaise, headache, and anorexia, which usually manifest 1-2 days before the outbreak of the rash. Rash -first appears on the scalp, face, and trunk. Pruritic erythematous macules comprise the primary exanthem, Progression through the papular stage to form clear, fluid-filled vesicles. Characteristic rash of varicella-lesions in multiple stages of evolution Contact dermatitis - is typically pruritic, has a pattern that suggests external causes (i.e., a linear distribution) Hand-foot-and-mouth disease presents with fever and constitutional symptoms, and then as white-grey maculopapular vesicles Herpes zoster presents as vesicular lesions distributed along a dermatome, in elderly/ immunocompromised patients