What breed is she? How old?
Alright, in rare cases, dogs can deliever one pup, and then take upto 24 hours until the next pup is born. It is okay if another pup comes after an hour or two.
If she is showing no signs of labor now or when the first pup was born, she might not have any. Some mommas don't show any signs.
If it has been more than a few hours (three or more) since the first puppy was born, you should take her in to be examined as there are most likely to be complications going on. With your dog still being a pup herself, and this being her first time breeding. Most dogs are fine and deliver pups fine. Sometimes there are complications just like any human pregnancy. In some cases, a C-section is needed.As for the other puppies, they should be fine as long as you take the proper precautions. Sometimes pups are fine, and sometimes they aren't, it's just a matter of genetics. My dog delivered a dead puppy, but the rest were fine, she had 13 healthy pups.
It is possible for her to go a few days after the first pup, however it is not heard of very often. That's why you need to get her checked out just to make sure that she is still doing fine and that the puppies are fine.
If she is still digging trying to find a place for the pups, then it sounds like she is fine and the pups are fine. She just miscarried a pup. With dogs and other animals, including humans, a fetus will abort if it has no chances to survive. Also, it can abort in order to make room for the other fetuses so that they can survive. When the miscarrage happens, it is usually the weaker one.
Keep a close eye on her and get her looked at.
You too. Glad to help. Good luck with the pups and momma!