Egg laying trouble

My pastel female laid an infertile egg about a week ago. I discovered it when I was cleaning the snakes' cages. I just removed the egg and closed her tub. She still looks pregnant, but haven't laid any more eggs. She spends most of the day coiled in a corner. I am getting too worried. I told my son, who works part time in a vet clinic to get an appointment to take her today, but he told me that the vet that works with exotics will not be there until tomorrow.
Is this a (somewhat) common occurrence? Has anybody had a similar experience? I have been breeding BPs since 2005 and this is the first time something like this has happened.

pictures of the snake will help.

Its not unheard of for a female to pass a slug before they lay their clutch. She'll probably lay the rest soon.

I just got home from work and found that she had laid 6 good eggs (total weight 599 grams). All eggs look fertile and she seems to be OK. She had mated with a Mojave and with a Pastel. Hoping for Pewters and Supers! :)

Good luck getting pewters out of that breeding. I think you meant Pastaves..:confusd::confusd::confusd:

You are RIGHT! Sorry I was thinking of another pastel female that mated w/ a cinnamon and a pastel