A person with peptic ulcer disease of the stomach, who undergoes no treatment and periodically has pain in the epigastrium and sour eructation, suddenly developed general weakness, palpitations, dizziness, and "coffee grounds" vomiting, later melena appeared as well. Objectively, the patient has pain in the epigastrium and positive Mendel sign. Blood test revealed the following: hemoglobin - 82 g/L, leukocytes - 7.5 109/L, ESR-22 mm/hour. What complication has developed in the patient?