What Causes Blood-stained Sputum?

Hi Dr, I am 32 years old. I have attacked by cough more than 2 weeks, I took some herbal medicine for the first time, after that I ate neofloxacin (1+0+1) and alatrol (0+0+1), after 2 days, i took ketotifen and i continued it for 7 days, my present status is ok, intensity of cough is low ( 2/3 times in a day). But the new problem is after sleeping today, i found small amount fresh blood in my liquid cough. Please give me some suggestion regarding this fact.