Hello. Thanks for writing to us at healthcaremagic A genital ulcer brings in many possibilities. This ulcer could either be a result of trauma during sex which may have become secondarily infected; else it can be an aphthous ulcer Or it can even be an STD like Herpes. STD s like herpes usually present with multiple lesions, there may be polycyclic erosive lesions and a grouping of erosions; a doctor on clinical examination would be able to discern that. However, this is a classical presentation of herpes and presence of solitary ulcer does nt necessarily rule out herpes. Aphthous ulcers on the other hand, usually present with central necrosis and peripheral erythematous margin; they may be solitary or a few in number and usually would not be grouped or form polycyclic lesions like herpes. Traumatic ulcers are usually solitary I would suggest you to visit a sexual health specialist for a clinical examination. If doubtful, your doctor might also order a few lab tests for STD s, particularly herpes. I would suggest you to use an OTC antibacterial e.g 2% mupirocin, twice daily pending appointment. A traumatic ulcer would heal if secondary infection is taken care off with the topical antibacterial. Regards