My dad is 64 and has had small cell lung cancer that he was treated for, and he now had a tumor removed from his brain that the doctors said was a result of the lung cancer. I was under the impression that this was going to be a simple operation and he was going to recover fine. I brought him home 2 days ago from the hospital when he was doing just fine, and now 2 days later he is not doing so good. His face is swollen, he wont eat, he is dizzy all the time, and today, he slept all day. I am worried. What should I be looking out for?