TMI!!! Spotting at 20 wk 1 day.

I have lately been having a brown spotting which otherwise isn't visible unless I run a tissue through my vagina and stick the tissue covered finger up my vagina. I have had no spotting in early pregnancy but now since last one week, this is happening though in very limited amount. My Dr says nothing to worry but I can't keep a handle on my stress. Has anyone ever faces this issue. I am a FTM and hence need some assurance. :(