What Causes Black Stool, Itchy Throat And Cough?

My husband was rushed to the hospital for internal bleeding in his upper gastro area. His BP was 98/68 in the ambulance, he was having black stool and breaking out in cold sweat and went unconscious on me. In the hospital they ran blood tests, x-ray and all the test. That night the doctor did an endoscopy but the bleeding stopped. The doctor found an ulcer and did a biopsy but the result will only be known later. My husband was discharged the next day deemed fit to return home. However for the last 3 days since he was discharged, his BP continues to stay at the low range of 113/66. He is having dizzy spell throughout the day. I know he s still unwell because he looks really pale and breaking out in cold sweat. My husband is 59 years old with heart condition. Since his discharged 3 days ago, he s still having black stool. The down side is my husband has gotten a cold while he was in the hospital. These couple of days he s having runny nose, itchy throat and cough. My questions are: 1) How long will the black stool stays in his system after the endoscopy? 2) Is there a possibility that he s still having internal bleeding as he s really pale and dizzy? Thank you for your advise.