Hello,

Have you been taking any iron supplements lately?

Now, worst case scenario is that there is bleeding somewhere in your gastrointestinal system. The darker the color, the further away it is from your anus region.

If this continues, maybe should consult a doctor.

Also, take more fibrous stuff. Fibre doesn't get absorbed and builds the bulk of your stool. Think of it as a thickener - when you take more, you thicken your stool.

Hope this helps.