How do i determine if cracks in a wall are due to the foundation sinking?

I have a home in the carribean and they had a flood a year or two ago, and last year I noticed some cracks in a few of the walls. This year they got worse. I had a few contractors come out and all say that ist nothing to worry about wthout doing any tests.
I checked the outside of the home and the same craks are visible on the outside. They are all in the same side of the house.