Have you had a structural engineer take a look at it? Have any large trees close? I had classic signs of issues and had one come out and he found I was outside of the acceptable levels on one side of the house.
Instead of foundation repair right away, he suggested I try a root barrier on one large oak tree and have a few smaller ones and a large pine on that side of the house taken out (between me and my neighbors), and then give it 12-18 months. My neighbor was having issues as well, and we had them taken out and I had a root barrier put in on a couple trees in the back yard, and in about a year and with some good rain, the cracks came back together and doors work perfectly now and have been that way for a couple years, and I have no signs of issues.
Worth a shot before dropping that kind of money.
