Pneumonia is not to be fucked with.
A surprizing number of young, otherwise healthy people die of it each year because they thought they were tough. Read about Jim Henson's death. I've never had it, but a doctor friend of mine explained it thusly: My lungs are always fighting of the various insults that get into them each time I breathe. When an infection, viral or bacterial, gets a start in my lungs, that is pneumonia. The problem is that lungs have to keeps working all the time; if an infection gets a "foothold", it has already overwhelmed your immune defenses. Absent some kind of intervention, you will die. Aside from that, the longer treatment is delayed from the onset of fever, the longer the period of recovery. My doc friend said that his rule of thumb is 1:8-- Add one day of recovery (after fever disappears) for every three hours treatment was delayed. In Henson's case, he delayed too long.