I thought your bitch had already whelped, do you mean she has a six week old litter, if so then bitches can have a discharge for a few weeks after wheelping. If it is unpleasant smelling though it could be an infection and you need to see the vet. :D
just to let you know it turned out that it was a phantom pregnancy with an infection. The vet did an x-ray and could see no puppies atall. He has given her antibiotics. he said to watch her incase of mastitus.