Happened to me irl. They didn’t tell me just how sick I got until I was awakened from my coma a month later. I was terminally ill for about 3 weeks (maybe even a day or so before I got to hospital. They really don’t know how I survived but I made it somehow).
Everybody has a watch that tells you how long you have until your death, most healthy people have years left on their watch but this boy has eight days left.