Grab for the adjective precarious when something is unstable, dangerous or difficult and likely to get worse. Are you totally broke and the people you owe money to keep calling? You're in a precarious financial situation!
The Latin root of precarious means "obtained by asking or praying." This fits well as precarious always signals that help is needed desperately. If your life is precarious or you are in a precarious situation, things could become difficult, maybe even dangerous, for you. If your footing or hold on something is precarious, it is unstable or not firmly placed, so that you are likely to slip or lose your grip.