After my boyfriend and I have unprotected sex my vagina gets very sore. I urinate frequently and in small quantities. Part of my vagina is swollen but doesn t hurt. Urination is very sore and as soon as I leave the bathroom I need to go back and it stings. I find that when I drink a lot of water throughout the day it gets less painful. I have had a smear test and came back clean. I also had antibiotics a few months ago for something to do with vaginal bacteria and she has no idea what it is.