Seems like the house is shifting or some support has been lost. How old is the house? What is the soil/ground/grade like around the house? Anyone else in the neighborhood experiencing this? It could be something as simple as poor workmanship like large gaps filled with putty. Or it could mean that part of your house has lost support due to rotting or poor support design. Worst case scenario would be the surrounding ground could be shifting or sinking. Unlikely, but possible.
I would investigate some more, but hopefully its as easy as a mudding and painting fix.