I'm a 16yr old female and I'm prone to UTIs as they recur after sex (every 6-8 months). One month ago, my second sexual partner and I had sex for the 1st time. I'm on the rod & he had no STIs, we also used a condom. After sex I showered & urinated to avoid bacteria but, within a few days irritation occurred like usual. I went to doctors in horrible pain as this was the worst I'd had before. She took a urine sample & prescribed 500mg Cephalexin. Throughout the many UTIs I've had, Cephalexin never seemed to work for me or family members. Within 1wk, symptoms still persisted. My unrine test came back with E.coli bacteria. She prescribed 500mg Amoxycillin & took another urine test for chlamydia & UTI. A week later I went back as I was still having trouble with uncomfortable urination, however it only occurred during the night. After urinating, within a 1min or 2 I'd feel the urge to urinate again but only release a few drops. She said the last urine test came back clean with no signs of UTI or STIs. She said maybe the uncomfortable feeling at the urethral opening could be due to irritated skin. She prescribed CORTIC-DS 1% ointment Hydrocortisone acetate & advised me to use this when irritation occurred. She also suggested if pain continued within a few days, I should get an ultrasound to check bladder & kidneys.  After still experiencing pain I decided to have the ultrasound. My results came back clear, with no sign of damage or other issues. My Doctor then took a swab test of the internal vagina and I found out today my results came back clear again with no sign of any problems. I've done urine tests, an ultrasound and swab test and I am still having trouble. What started as a UTI from sex has turned into something else that I am unsure of. Although the antibiotics helped for the UTI and the ointment has helped with majority of the burning, I am still having discomfort after urinating and the urge to urinate again. I'm drinking 2L of water everyday since I first had pain from the UTI & I've been careful of foods I eat & showering everyday. I've been drinking cranberry juice and taking cranberry tablets. I've also recently today been placed onto 50mg Doxycycline for acne reasons. I'm not sure what else could be causing this pain if I no longer have a UTI? Are there any possible causes or tests to help understand the problem? Has anyone else experienced something like this?