Okay so , I think I have an STD . I talk a shower every day , so I smell clean before I go to bed . But the next day , as the hours go by , an odor begins to always form inside my underwear . Like if I open my legs up (slightly), I can smell it. For some reason, it smells very damp . As if I am very moist . Sometimes I have marks on my underwear: light yellow or a light brown . Someone please help .