Gastroesophageal Reflux Disease (GERD) with erosive esophagitis: This condition is common and can cause vomiting with blood due to esophageal irritation, even with a recent negative EGD, as the esophagus can become irritated between endoscopies. The stable hemoglobin level suggests that the bleeding is not severe.

Peptic Ulcer Disease (PUD): Although the recent EGD was negative, ulcers can develop quickly, especially if there has been a change in medication (e.g., starting NSAIDs) or an increase in Helicobacter pylori infection risk. The presence of blood in the vomit (hematemesis) is a classic symptom.
Mallory-Weiss Tear: This is a tear in the mucous membrane or lining of the lower end of the esophagus, where it connects to the stomach. It can be caused by intense or prolonged vomiting, retching, or coughing and can lead to bleeding.
Gastritis: Inflammation of the stomach lining can cause vomiting with blood. It can be acute or chronic and is often associated with Helicobacter pylori infection, NSAID use, or alcohol consumption.

Esophageal Varices: Although less likely given the stable hemoglobin and recent negative EGD, esophageal varices due to liver cirrhosis or other causes of portal hypertension can cause severe, life-threatening bleeding. The absence of other signs of liver disease does not rule out this possibility entirely.
Gastric Cancer: While rare, especially with a recent negative EGD, gastric cancer can cause bleeding. It's essential to consider this, especially if there are other risk factors or symptoms such as weight loss or abdominal pain.
Dieulafoy's Lesion: A rare cause of gastrointestinal bleeding, characterized by a small mucosal defect with an exposed, often large, caliber artery at its base. It can cause severe, recurrent bleeding.

Hemobilia: Bleeding from the bile duct into the gastrointestinal tract, which can be due to trauma, tumors, or vascular malformations. It's rare but should be considered in the appropriate clinical context.
Angiodysplasia: Vascular malformations of the gastrointestinal tract that can cause bleeding. They are more common in the elderly and can be associated with other systemic diseases.
Ingested Foreign Body: Sharp objects can cause bleeding if they penetrate the esophageal or gastric wall. This is more common in children or in individuals with a history of eating disorders or other psychiatric conditions.