What Causes Blood In Cough And Pain In Chest And Back?

Hi, i am coughing up blood a few days , it is small amounts of blood with secretions , that occur after violent coughing because i have been seek a few days , and i also concluded that the i cough up blood after lying down, (in the morning , after sleeping), right now i am feeling pain in the chest and my back ( i think that is from bag cough) it occur just 4 time for 6 days, and the last time was today, and it was very very small amount of blood and was not very red ( the last 3 times was very red and mucous ), I am 26 year old female, and smoker for 8 year. I am very concerned , should it be from prolonged coughing? Thanks