HELP-surgery went well but now?

Help has this happened to anyone else? My mother-in-law had surgery a month ago for kidney cancer all went well and the surgeon said he got it all. She was released from the hospital a week later but she got worse. She went to the emergency room 3 times the next week the 3rd time they admitted her. She had pneumonia and bacteria in the blood. She is so weak and her legs and feet are so swollen. Now two weeks later she isn't any better what do we do?