I had it too and got rid of it after 8 weeks of anti biotics. You can have it from some sexual contact, but you can also just be unlucky to get an infection at that spot without any kinky sexual behaviour. Swimming in a lake or any other untreated water... any contact with contaminated matter. In my case i just assume i got it when having sex with an infected person, i had chlamydia before too which also needed a long anti biotic treatment. Problem is these bacteria become resisrent.