Q. A 38-year-old woman presents to the emergency department in late summer with complaints of a progressively expanding skin rash over her left thigh and a one-week history of fatigue and joint aches. The rash started as a small red spot and has expanded over a week into a large ring-shaped lesion with a clear center, measuring about 10 cm in diameter. She reports hiking in a wooded area in the Northeastern U.S. a couple of weeks ago but does not recall any tick bites. On further examination, the patient's temperature is 37.5°C, pulse is 75 beats per minute, and BP is 120/80 mmHg. She appears fatigued and reports mild headaches. A full physical examination reveals mild swelling in the left knee with tenderness but no effusion. The rest of the physical examination is unremarkable. Lab findings include normal complete blood count, mild elevation of ESR at 25 mm/hr, and normal liver and kidney functions. No abnormalities are noted on knee joint X-ray or chest imaging. What is the next best step in the management of this patient?