Hi, my father-in-law has been detected with 4th stage lung adenocarcinoma, june, this 2017. He is having a history of tobacco chewing. Pet-ct and ct scan suggested that cancer has spread to lymph nodes and some part of abdomen. He completed his chemotherapy with carboplatin and pemetrexed. From oct 2017, he is on erlotinib and completely fine, but from last week, his cough increased a bit, more importantly, he is having fever and weakness from this sunday. What could be the reason, is it related with cancer or it is general fever?