We are in southern Illinois and last Sunday my wife noticed a crack above the kitchen cabinets. We started looking around and have found cracks all over the house in different areas that were not there before. We are starting to see seams in the drywall in different place and nail/screw heads through the drywall. The paint is pulled in many places along where the walls ceilings meet. The windows are out of square (were not before). And almost all the trim in the house is pulled away from the ceiling. We have paneling in one room and it has pulled away in the corners. The wall behind the fireplace has started to pull away from fireplace. Gap gets bigger as you go up. Would this be shifting? Worried because this has all happened in a weeks time. Here are some pics.
Have you checked at your water meter to see if it looks like you are consuming an excessive amount of water? It could be that your under ground water feed into the house has sprung an underground leak near, under or within your foundation. Being under ground it is possible that it could run leak for a long time and you would never casually observe it. A steady flow of water into the ground in such condition could lead to a serious settling problem such as you describe where many things could change quickly over a short period of time.
This should be easy to check. Write down the reading from the water meter one evening and then check it again the next day. Of course allow for a nominal amount of usage for toilets, a shower and your drinks.
I've encountered the same problem in my own home, although the drywall and ceiling seam cracks only showed up one at a time over the course of a few years, and most of them were present when I moved in. If more than one or two seams popped or nail heads started showing within a month, that seems like it could be a rather large settlement in your foundation, or some other structural problem.
I'd highly recommend getting a foundation specialist to your house sooner rather than later to see if your foundation might need piers to support part of it, or if some other repair is required. In my house, a total of 14 piers were needed along the side and front of the house to support one side and prevent further shifting. There were a few hairline cracks (even small cracks can be a bad sign depending on where and how many they are) in the foundation walls, and the corner of the house had settled over 2" before the problem was found.
The problem could also be in load-bearing structures (walls, I-beams in the basement, etc.), especially if it seems the problems are mostly towards the middle of the house.
The sooner you get this fixed (don't just let it go, even if you have to pay a few thousand), the better. You'll avoid more drywall repair later, and prevent further settlement and degradation of your house's structural integrity.