Structural problems in residential property

I continue to have new cracks appearing and old cracks growing larger each week in my 1991-built home. When do I become alarmed that this is a safety concern for my family? What recourse do I have in getting a professional assessment for the damage without my having to pay for it? Do I go to the city which approved home development in my town? Do I go to the home builder (who since has sold to another local developer)? Thank you for any help anyone can give.

-Ed, Gilbert, AZ