A little settling is often common; a lot of settling may be due to a more serious problem. Often, Contractor Insurance only covers his work for one year after the work is done; however, if he did not do the work properly, say according to codes, you may have legal recourse. A professional would know.
Sometime settling is due to building supports not placed below the snow-lines. When it freezes the soil expands and contracts raising or lowering poorly installed concrete posts. If the shearing or cracks have finally stopped after two years, this luckily may not be one of your problems.
Sometimes reinstalling or re-lamination sheet rock that spans over the cracked area often solves the problems of minor expansions and contractions. I have seen carpenters not, "Flag" their sheet rock over doorways and after a some time, it often cracks. Opening the ceiling may show you some problems with the construction there, then again it may not, but at least you know what you will know. I have found that taping with nylon mesh tape or adding more sheet rock screws doesn't really offer a permanent solution to a serious problem. It may work for you. Sometimes it's worth paying a little extra in the first place to have a reputable company do the work. If you want cheap now, what I suggested may be worth a shot.
