A 30 year old woman presents with pain on urination. She is empirically prescribed a course of trimethoprim/sulfamethoxazole but her dysuria persists. On examination, you note painful genital ulcers and tender local inguinal lymphadenopathy. There are multiple pustular vesicles and ulcers that arise after a 4 day incubation period and last 2-3 weeks. In addition, she complains about fever, headache, malaise, and myalgias.
Challenge: What's the most likely diagnosis?