dear user about your question i would like to tell you that these symptoms of pain with burn sensation of urethra refer to having urinary tract infection urinary tract infection may be due to viral or bacterial infection....so if you found small blisters around penis with itching and itching it suggest viral infection of hsv2 that aquired by sexual contact you did urine analysis and the results lead to bacterial infection suggestion ....you need to do urine culture as primary investigative test of bacterial infection as in this case you should have antibiotics for treatment ...althaugh you administerd bactrim but it may have no effect as there is bacteria may resist it.. and urine culture and antibiotic sensitivity test will detect simply the way of treatment and selection of the approbriate antibiotic that will give best results with bacteria detected......you may not comlete the course of treatment so bacteria not eradicated......discuss with your doctor to do urine culture and antibiotic sensitivity test as it will help alot.......you should drink alot of fluids and avoid your sexual activity untill treatment completed........wish you healthy life