My crown hurts when I bite down on it. Its over 2 years old and never hurt before..?

Its really sharp pain, but it doesn't last long. It is giving me headaches when it hurts. I was recently in a very minor car accident but I clinched my jaw so tight I think that might have some how damaged it? I don't have dental insurance any longer and would like to avoid spending that money at this time if I can... any advice?