A 9-month-old female infant is brought to a pediatric clinic by her parents due to a sudden onset of a generalized rash. Four days prior, she developed a high-grade fever, peaking at 39.7 C, which persisted for 72 hours without any other accompanying symptoms. The fever completely resolved yesterday morning. Her parents report she has maintained excellent hydration and her usual playful demeanor throughout the illness. This morning, a non-pruritic, maculopapular rash appeared, initially on her trunk and then spreading to her neck and proximal extremities. Her immunizations are up-to-date. On physical examination, her vital signs are temperature 37.0 C (98.6 F), heart rate 110 bpm, respiratory rate 28 breaths/min, and blood pressure 90/60 mmHg. She is alert, interactive, and well-hydrated. Oropharynx is clear, and there is no lymphadenopathy. Cardiopulmonary examination is unremarkable. Abdomen is soft, non-tender, with normal bowel sounds. The rash consists of blanching, discrete, rosy-pink macules and papules on her trunk, neck, and proximal extremities. No vesicles or petechiae are noted. Her mother is concerned about the cause of the rash. What is the most appropriate initial management for this patient, and what potential complication should the parents be advised to monitor for?