Both of my rib cages have been hurting me for the pass 4 days. what is this? what causes it?

Rib cage: I would be suspicious of some low grade muscular inflammation or strain. Have you performed any exercises or work related activities that could have stressed your rib cage or chest wall? Have you been exposed to extreme winds, drafts, air conditioning,etc that could have been blowing on your torso? Any signs of a viral illness? See your MD if Tylenol (acetaminophen) or Advil don't help or if you develop a cough.