for the past couple months i have noticed that my vaginal discharge has been changing colours (yellow,brown,milky white) that has a scent attached to it. not only that, but my vaginal area has been itching a lot and it burns sometimes when i pee. if i rid myself of waste when im wiping up myself there is blood. do i have an std or is it something else?? because i took an HIV, chlamydia and syphills test and they all came back negative.