Here are three great songs that all seem to have something to do with sickness. That's weird, right?
"Cough Cough" by Everything Everything (which is "about having no money, and wanting more money, and wanting nothing to do with money at all," according to the lead singer, so maybe only metaphorically about sickness?)
"Cough Coughing" by Menomena
"Germs" by Yeasayer