Conversation: The conversation between human and AI assistant.
[|Human|] My father is diagnosed with stage four lung cancer. He coughs persistently but has no pain. He underwent four cycles of chemo and stops. However, he start coughing up red mucus and some strange particles and stooling very black stool since five days past. Now the blood in his phlegm stops yesterday but his stool is still black. What does this mean? Thank you for being there for us - Femi George
[|AI|]  Hello;welcome to ChatDoctorSorry to hear about condition of your father. In advanced lung cancer, there can be bleeding from tumor into the airways. That can be the cause of red mucus in his cough. Black stool means he has bled somewhere in his G.I. tract. Sometimes patient having bleeding in airway can swallow it and develop black stool. You mentioned your father recently received chemotherapy. Internal bleeding a sometimes occur after chemotherapy if blood counts are very low. You should inform your doctor regarding these symptoms. Regards