Hi there...I can understand your concern. From your description it looks like you could be suffering from chancroid, herpes genitalis, syphilis or gonorrhoea. It can be a non std like traumatic ulcer or contact dermatitis also. You will need detailed clinical examination and further investigations to confirm the diagnosis. Treatment for all the conditions vary. So it's important to confirm the diagnosis. So kindly consult a dermatologist for further evaluation.