You can have a foundation repair company come out and give you a quote, but before you pay to have your foundation repaired, have a structural engineer (civil engineer) come out to give you their solution.
We live in New Braunfels and had a reputable foundation repair company come out after we noticed some cracks - they found that one side of the house had dropped 3 inches, and quoted us $18,000 to fix it with beams that went down to the bedrock. At the recommendation of someone on here, we called a structural engineer, paid $250-$300, they discovered the same measurements, and gave us reasons why we were having these foundation issues after the house has been standing for 20 years and instructions on where to bury a soaker hose that would fix the issue within 6 months. They'll come out again at that point to re-measure, etc.
We used MLAW, and I believe they have a Houston office.
http://www.mlaw-eng.com/