I have a major crack that has worsened on the ceiling drywall of our bedroom. It is located at the base corner of a pop-up and runs from the corner to the wall (About a foot and a half). I went into the attic to have a better look and sure enough the crack goes completly through the drywall(I can see light from the bedroom below through the crack. Our house is located in Texas and is over 18 years old so it has been around awhile. We have been in it two years. There are no cracks in the walls so I hope this is not a foundation problem, but maybe just some shifting or settling. I see some smaller cracks begining on the opposite side as well. Finally, it appears that the previous owner might have made repairs as the texturing is slightly different. I have two questions.
1) What might be causing this to occur? Is this a major problem? 2) What is the best way to repair a crack that has gone all the way through the drywall.