Hi, I had gone through your question and understand your concerns. Cough usally not cause any bleeding in ear. He must have also common cold which can cause bullus myringitis ( small boil over ear drum) and when this boil gets burst, it can cause little bleeding. As, now there is no active bleeding, you should not worry. He must take treatment of common cold and cough. Keep ear dry, dont allow water to go inside of ear. Hope this answers your question. If you have additional questions or follow up questions then please do not hesitate in writing to us. I will be happy to answer your questions. Wishing your friend a very good health.