burning down there

so 2 months ago, I went and got myself checked because I was having a fishy odor down there. I had bacterial vaginosis, and all the other tests came out negative. They gave me antibotic for a week. my odor went away but sometimes it burns really down there only at night when I hace to pee so bad or something. its like this burning irritation. when I pee and at the end SOMETIMES there is this sharp discomfort. but why does it burn? the inside of the vagina is what burns not the outside.