Hello Dr. I travelled in a flight from India to Dubai very four days before. And sometimes before landing I felt severe headache. After reaching Dubai and having food when I cleaned my mouth with water blood stains where mixed with the cough. But for two days now its not there except in the morning first time wash, and its very dark black in color. I don t have any other problems like pain or anything. PS : I am a non-smoker and also don t drink.