Pain urinating, antibiotics not working, very painful cramps

I recently had sex with a guy and we used a condom however i have been experiencing uti symptoms since. I have had many uti's in the past and assumed that was wat it was so i went to the doctors and got antibiotics, however i have been on them a week and it has not gone away. I have also got my period but the day before i got them i was hot/dizzy and having severe adominal pain and nausea. I have only had my periods for a few days but they are very light compared to usual although there is alot of clotting and alot of it is dark brown blood. I have also been under a lot of emotional stress lately. Could my periods be affecting the effectivness of the antibiotics? i have heard bacteria breeds in blood.. any advice would be appreciated