If you are having blood in your stool and it is dark in color then it is likely you are having bleeding higher up in your GI tract and I think the colonoscopy and endoscopy is a very good idea.
thanks for responding constipation is off and on not consistant but everyday same nausea feeling and symtoms described earlier
I had the same symptoms for 15 months, and I got finally diagnosed with parasites. Ask your GP for the scotch tape test (yes, it is for kids, but grown ups can have them, too).