Recent diagnosis for my dad

Hi everybody. My dad is 69. Until last year was fit & active. Young for his age you might say. In March 2015, however, he was diagnosed with cancer of the tonsil -it was fairly extensive T3 & had travelled to the lymph nodes. The doctor said "there's nothing here that I can't zap I am sure". If only. My dad went through chemotherapy which he tolerated well. He then had 30 doses of radiotherapy which, because of the location of the cancer, meant that he suffered enormously with horrendous mouth ulcers. He couldn't eat, speak or drink and relied totally on a feeding tube in his stomach (PEG) for his nutrition & medication. He also had a neck dissection to remove the lymph nodes on the left side as some had been resistant to the treatment. We were told that one was "leaking". He began to recover slowly & even started eating soft foods. Following another scan, however, the doctor suspected that there was further cancer in the throat. My dad had a pan endoscopy biopsy from which he hasn't recovered. The pain is now unbearable again. The biopsy showed no cancer. He also had a biopsy through needle aspiration. This showed no cancer. Because his symptoms are still severe In the throat, they are assuming that there is still cancer there but the biopsies haven't shown this. Could the 2 biopsies have failed to detect the cancer? Could the pain still be caused by the treatment and the huge biopsy on newly formed tissue? Last week, my dad was admitted to hospital to try & help manage the pain & also to help undergo further tests. This revealed that he now has a small (2.5cm) tumour on the lung. The doctor feels that this will be a secondary tumour having travelled from the throat. She feels that to biopsy this will be too much for my dad. She plans to try chemotherapy to help shrink the tumour & provide some quality of life - he has none at the moment - his pain is being managed by such a huge drug regime that he is exhausted. He is home now. He isn't eating. He is sipping the tiniest amount of liquid. It is breaking my heart. He has struggled so much, I just want him to have a little quality of life. What if she is wrong though and there is no cancer I the throat and the cancer in the lung is a primary which could be operated on? Any advice would be so appreciated x