What does it mean when i have green poops that were sticky and then went black and sticky for a few days.  I have stage 4  lung cancer that has gone to my liver.  I also have been very constipated and had to take 4 sena-s a day and a natural veg. laxative and miralax daily.
The picture that you have described is called galena. It is due to bleed somewhere in the upper intestines or stomach. This can happen spontaneously in a cancer patient or due to any therapy that he may be on particularly chemotherapy. Get a stool for occult blood and an upper GI endoscopy done. That will confirm whether there is bleeding and also show the site.