How long has she been vomiting?
How much blood is she vomiting? Is the vomit blood tinged or a lot?
If there is a lot of blood? If so, could she have eaten rat poison?
If she is vomiting a lot of blood, you should get her to a veterinarian ASAP.
The mouse droppings and possum fight should not have caused this.
Bleeding stomach ulcers or tumors could. Low platelet counts (thrombocytopenia) is another possible cause.
Can you get her to a veterinarian?
There is nothing that you can do to stop bleeding from the stomach at home. If the blood is from the mouth, it might stop on its own. You can wait and see if it stops without treatment, but run the risk of losing her if she continues to lose blood.
There are some causes of bleeding that a veterinarian can treat, but again, if she is really bleeding a lot, it could be hard for a vet to get stopped also.
If you keep her at home, keep her as quiet as possible and don't give her any food or water for at least 4 hours after she stops vomiting and bleeding. Then start with very small amounts of water every 15 minutes for several hours before offering her tiny bits of food.
Not giving her food or water won't affect the pregnancy.
Is she still vomiting blood?
Good.
Are you giving her any aspirin or other pain meds? If so, they could make bleeding worse.
Veterinarian
30 years as owner of a mobile practice treating dogs, cats, horses and other pets.