Thank you for your query at DoctorSpring.com
I understand your concern.
The bump could be due to trauma suffered while intercourse, or could be a sore. It is difficult to say without looking at the bump, however a couple of things go in favor of UTI. Firstly a constant burning sensation and secondly the leukocytes being positive in the UTI test.
The possibility of Herpes remains, even if your partners claim they are clean. At times the person can be a carrier, without any symptoms and can transmit the infection to his sexual partner. And then all genital herpes also do not have the same presenation with a full blown rash and sores. It is better you take the HSV-2 IGM test done and based on that we can decide your further course of management.
Feel free to discuss further,