I have had nausea and black stools for 2 days now no pain at all just dizziness and weakness??/

Black stools: Black stools often are present when there is bleeding from the stomach or upper gastrointestinal tract. They also occur while taking iron supplements or peptobismol. I recommend that you see your physician who will perform a simple stool test checking for evidence of blood in your stool. Of course if profuse passing of black,tarry stools and weakness occur, proceed to the hospital emergency room.