Scott is a 42-year-old cisgender man with a past medical history of hypertension and diabetes who presents with rectal pain, rectal bleeding, tenesmus, and constipation for 6 weeks. He has no known history of inflammatory bowel disease. He is sexually active with men only and has insertive and receptive anal sex without condoms. He takes emtricitabine/tenofovir disoproxil fumarate (FTC/TDF) for HIV pre-exposure prophylaxis (PrEP) and reports testing negative for HIV two months ago. Visual exam reveals an anal ulcer. Lymphadenopathy is noted in the bilateral inguinal regions. You swab the ulcer for herpes simplex virus-2 (HSV-2) and obtain rectal gonorrhea and chlamydia nucleic acid amplification tests (NAATs). The patient is also tested for syphilis and HIV. Point of care HIV screening is negative and RPR is non-reactive. Based on his clinical presentation, what single empiric treatment is most appropriate?