A 32-year-old woman attends the STI clinic with a 6-week history of rash involving the trunk and palms, generalized lymphadenopathy, fever, and malaise. She reports a history of a painless ulcer on the vulva 8 weeks ago that healed spontaneously. RPR is positive (1:32), FTA-ABS is positive, and blood cultures are negative. What is the most appropriate next step in management?