Vomiting blood
http://www.mayoclinic.org/symptoms/vomiting-blood/basics/definition/sym-20050732Vomiting blood (hematemesis) refers to significant amounts of blood in your vomit. Small streaks or flecks of blood in material you spit up may come from the teeth, mouth or throat and isn't usually considered vomiting blood. Blood in vomit may be bright red,
or it may appear black or dark brown like coffee grounds.Swallowed blood, as from a nosebleed or forceful coughing, may cause bloody vomit, but truly vomiting blood usually represents something more serious and requires immediate medical attention. Bleeding in your upper gastrointestinal tract (mouth, esophagus, stomach and upper small intestine) from peptic ulcers or torn blood vessels is a common cause of vomiting blood.
Call 911 or your local emergency number if vomiting blood causes dizziness after standing, rapid, shallow breathing or other signs of shock.
Vomiting blood may be caused by:
Acute liver failure
Alcohol use disorderAspirin
Benign tumors of the stomach or esophagus
Cirrhosis (scarring of the liver)Defects in gastrointestinal tract blood vessels
Dieulafoy's lesion (an artery that protrudes through the stomach wall)
Duodenitis (inflammation in the first part of the small intestine)
Esophageal cancer
Esophageal varices (enlarged veins in the esophagus)
Esophagitis (inflammation of the esophagus)
Gastric erosions (breakdown of tissue lining the stomach)
Gastric varices (enlarged veins in the stomach)
Gastritis (inflammation of the stomach)
Mallory-Weiss tear (tear in the esophagus associated with pressure caused by vomiting or coughing)
Nonsteroidal anti-inflammatory drugs
Pancreatic cancer
Pancreatitis (pancreas inflammation)
Peptic ulcer
Portal hypertension (high blood pressure in the portal vein)
Prolonged or vigorous vomiting
Stomach cancer
https://en.wikipedia.org/wiki/Coffee_ground_vomiting