A 19-year-old man presents with a widespread rash that appeared suddenly about 5 days ago. He mentions having had a severe sore throat approximately 2 weeks prior. On examination, there are numerous small (0.5-1.5 cm), discrete, erythematous, scaly papules and plaques distributed mainly over his trunk and proximal limbs. There is no significant joint pain or nail changes noted. What is the most likely diagnosis?