I am 23 years old heterosexual, male. Had unprotected oral sex performed on me from a woman. Couple of days later i had the urge to go constantly pee and when i did i felt i burning sensation. 5 days after my enconter with that lady, I went to the doctor to get an std test for Ghonorrhea and Clamydia (pee test) and both came back negative. Doctor prescribed me with some medicine ( phenazopyridine & ciprofloxacin ). Yesterday night, a day after I visited the doctor and began taking the antibiotics. I felt a sudden pain in my lower back and lower abdomen, the pain in my lower back has not seazed and my lower abdomen pain comes and goes. Is it possible the std test came back negative becuause it hadn t been that many days after the unprotected oral sex, or am I looking at a urinary tract infection? Thank you