Crown came loose, tooth had root canal. What is under the crown? Will it hurt if I take off crown?

Back in 2006 I had a root canal and crown placed. Today I have had pain around the crown. When was flossing I pulled the floss out it must have dislodged the crown and it became lose. I bit down and pushed it back into place. My question is, what is under crown if it falls out? How painfull will it be? It is Friday night and I don't have dental insurance, I can not afford emergency dental visit at this time. What will be exposed under crown?