My Girlfriend Says She Take A Pill Prescribed To Her

My girlfriend says she take a pill prescribed to her a couple of years ago that was white about the size of a children's aspirin. She went to the doctor thinking she had a UTI, was the test was negative. She would have after having sex or just thinking about sex she would start cramping and the pain started in the area of the bladder and extended upwards towards the kidney area. She doesn't remember the name of the little white pill, but it helped her a lot with her condition. I'm not sure whether it was an antibiotic or what. The urine test showed protein or albumen so they rule our UTI. She told me that it only happen when she had sex for the first time or two, then it would subside as she had sex with the same man multiple times. I am not sure if it's a STD or vaginal irritation. Thanks for any advise you can give !! Michael