
Hi, i give my girls collocal D after whelping, it can be a lack of calcium that causes behavior like this, but she has only one pup so it might not be that.
I think maybe you should take her to your vets for a check up, you will be able to get the Collocal D there too.
It is normal for them to pant and dig as she will be having after pains and yes its normal to leave the whelping pen to go to the toilet.
Your vet might scan her to see if there is anything left inside.
Congratulations on your puppy.
LIz