Honestly, I kind of feel like this sometimes. I certainly don't have anything as bad as the things talked about in the song, but I'm almost always vaguely sick in some way. Then, when I go to see a doctor, they do every test under the sun, including blood work, and just come back with a "Well, you're perfectly healthy, so maybe try some antibiotics and drink water?" I've come to the conclusion that I'm just weird, and I just have to deal with it.