What Causes Vomiting Of Blood With Sore Abdomen And Black Stools?

On friday i threw up from 7pm-11pm constantly. I couldn t keep anything down. I threw up blood about five times. I went to the ER they did a CT scan said everything was fine and that i had gastritis. Yesterday and today my stomach is sore. I am now starting to have a fever and my stools are black. What is happening to me?