My girls always have a discharge about 2-3 weeks before they whelp.. When you say your girl is spotting are you talking just discharge or a bloody discharge? I just had a girl of mine start to spot with a bloody discharge and she lost her litter.. I ran her to my vet right away and the litter was gone! My vet has put her on an antibotic to make sure that she does not get an infection..
Please keep us updated on your girl and let us know when she whelps and be sure to share pictures of your babies..
Melanie