A 39-year-old man, a battery attendant, suddenly developed weakness, loss of appetite, non localized colicky abdominal pains, and nausea. Objectively his skin is gray. there is a pink-gray stripe on his gums, the stomach is soft and sharply painful. Blood test detected erythrocytes with basophilic stippling and anemia. The patient has a history of peptic ulcer disease of the stomach. Constipation tends to occur every 3-4 days. What is the most likely provisional diagnosis?