will see that it fluctuates quite alot. I mean during droughts, it shrinks and actually causes the house to settle deeper, then when a rain comes, its like a sponge and fills with water and then rises. The house goes up and down with the soils.
Normally cracks open up in the summer and close in the fall and winter with the moisture.
Do you have a water weeping hose fastened around your home for watering? Or can you use water this way?
None of this will fix your foundation problem just might ease it a bit.