
If it is less than 6 weeks since a possible mating then she can still be given the Alizin injection to terminate the pregnancy.
A scan from a competent vet should be able to determine a pregnancy, and if pregnant then administer the Alizin and she will absorb or abort depending on how far she has gone.
It will be a little unpleasant for you and uncomfortable for her, but better than rearing an unwanted litter, especially so soon after the last.