Puppy has blood-filled bumps near her vaginal area. What should I do?

This could be a sign of puppy pyoderma, trauma (is she licking the area a lot?), insect bites, or signs of a viral infection/fever, rodenticide ingestion, a congenital or acquired disorder affecting the platelet's ability to adhere to damaged blood vessels.
If these blood "blisters" keep enlarging or do not go away within a few days, you will need to consult your veterinarian. The vet will perform a thorough physical examination. Lab tests will be necessary such as a complete blood count, biochemistry profile, and urinalysis and possibly a coagulation panel.
There is no specific treatment for those blood filled skin lesions, however it is important to find the underlying cause, which then can be addressed.
So, I suggest you monitor the skin and if the lesions enlarge, or if they do not go away within a few days or spread, you take your puppy to your veterinarian. If your puppy gets pale gums it is an emergency and your pup needs to be seen at an ER right away.