Tonya, if your filling fell out, then the nerve is probably exposed to the air and that is why it is so painful.
This happened to me also and I couldn't see my dentist for a few days. My dentist told my to get a cotton ball and take a piece of it, just enough to pack the tooth with and this will stop the air from getting to the nerve. I did it and by the next day I had no more pain.
Good luck in whatever you decide to do, cause nothing is worse than a throbbing toothache.