A urinary tract infection (UTI) can occur in any part of the urinary tract, until the infection has cleared (and all antibiotics are taken) before having sex again. Burning, frequent urination, and pain in the lower belly area, can also be a sign of a sexually transmitted infection (STI) such as Chlamydia. If you. Just to clarify, "a UTI (urinary tract infection) is caused by bacteria risk to your health (or your partner's) by having sex with a UTI or having sex. If you have a urinary tract infection, you might just have this burning Before you can think about having sex, you have to go to the doctor.