Brief Answer: may be due to viral infection Detailed Answer: HI, thanks for using healthcare magic The brown/black mucus is the blood in the mucus. Blood may have a brown/black appearance because it becomes altered. Blood can be found in mucus for different reasons such as: (1)viral or bacterial infections such as bronchitis, pneumonia, rare conditions such as TB (2), trauma to the chest (3)the presence of a foreign body in the chest (4)fungal infections (5)related to blood vessels in the lungs (6)cancer of the lungs (7)bleeding due to infection of the nasal passages and throat- this can also occur in viral illnesses such as the cold or flu (8)pulmonary embolism- this occurs where a there is a clot in one of the blood vessels in the lungs The most common cause is infection usually viral or bacterial. Out of these viral infection occurs more often. She may have a viral chest infection. Pain can occur as a result of the persistent coughing and also because the infection can sometimes irritate the lining of the lungs (pleura) and this causes pain. The treatment would depend on the exact cause. It would be best to be assessed by her doctor by physical examination to rule out other possible causes The doctor may consider the use of a mucolytic agent such as bisolvan/mucomyst/robotussin to decrease the viscosity of the mucus and make it easier to come out. In addition the use of a cough suppressant may be suggested to reduce the frequency of the coughing. Paracetamol would one of the safer medications for the pain. She should drink a lot of fluids to decrease the viscosity of the secretions and get as much rest as possible. I hope this helps, feel free to ask any other questions

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