What Causes Burning Sensation During Urination After Intercourse?

So I've only had sex with one guy and two days after I had sex it burned really bad to pee & then two days after that it itched really bad. I went and got medicine for an UTI and that didn't work so last Thursday I went to the doctor and she said it could be a STD but my partner said he's clean. Then the doctor said I have two small bumps by my pee hole and that's what is causing the burning when I pee.