28 weeks pregnant, tmi warning?

Hi-Im 28 weeks today (yay), I have a marginal placenta previa, and I am not sure if I should worry. When I go to the bathroom today there is that period smell, if you know what I mean, Like how you can smell the iron or whatever in the blood? There is no blood no spotting or anything, just the smell of it, so I'm not sure if I should worry? I know if there is any spotting or anything like that I should call the doctor, but since there isn't I'm not sure? Baby is moving just fine all day so far....