Hello, Thanks for your query. It could be from dry sex and friction or the lube you used. In this case it will heal spontaneously and will turn dark red to black within a week. But if the ulcer is increasing in size, very painful, discharging along with inguinal lymphadenopathy it may be an indication of sexually transmitted disease for which you need to visit a veneriologist to get examined and go through a panel of test. But right now you just keep watch on the progression of ulcer. Thank you.