It can sometimes be difficult to tell the difference between
vomiting blood and coughing up
blood (from the lung) or a nosebleed.
Conditions that cause vomiting blood can also cause blood in the stool.
Causes
The upper GI tract includes the stomach, mouth, throat, esophagus, and the first part of the small intestine. Blood that is vomited may come from any one of these places.