Can A Cough Syrup With Codeine, Zicam Or Garcinia Cambogia Cause Dark Stool?

I am currently taking the following medication and supplements: cough syrup with codeine, Zicam (zinc), and Garcinia Cambogia, can any of these be the cause for dark stool? I have noticed a change in my stool to dark, soft and tarry. No Abdominal pain.