I bought a house two years ago (50's). There was a small crack in the bedroom ceiling which is at the corner of the house. Since, we have pulled out the carpet and noticed that the one corner is actually lower than the other three (marble tested). This is also visable from outside the house. Anyway, the crack in the ceiling is getting bigger and bigger (and wider). It seems the house is settling but to a great extent. I don't want to re-drywall the ceiling w/o fixing the bigger problem. Can anyone give me any insight or suggestions. We have a 4 foot crawlspace below (not on a slab).