Mum still coughing up blood AFTER cancer?

My mum had lung cancer and went through the whole chemotherapy and radiotherapy, but has been clear of cancer in 2007... recently about 4 Months ago she was diagnosed with cancer, she had to get her whole removed and she is now again been clear of all cancers, confirmed by her her specialist through her cat scan a couple of weeks ago. She has been coughing and coughing severely, but she is only coughing at night, mainly when she is laying down and it's wearing her down, she has been out of hospital for 4 weeks from her operation, and because she coughs her side has swollen up and is painful for her.... Her coughing started from about June when she was diagnosed with pneumonia and she has been coughing ever since, but her coughing up blood has only started since her operation