I am sorry to hear you are worried about Gump. My name is Rebecca. I am a veterinarian and will do my best to help.
If you check her gums, are they pink in color, or do they seem pale? If her gums look pale, she probably should see your veterinarian.
Is she eating today? Is she at least drinking?
It sounds like she ate something that is now causing digestive problems. More than likely it is something that will pass with rest, keeping her quiet and keeping her hydrated. If she continues to have diarrhea, you could try a dose of Pepto Bismal or Imodium. If you tell me what she weighs, I can give you a safe dosage.
One thing that is more serious that can happen after getting into garbage or trash is pancreatitis. However it is seen more in older dogs. The signs of pancreatitis are vomiting, not eating, pain, diarrhea.
If you take her to your vet, you would be able to get prescription medication that would be helpful. If you want to see how she does at home another day, keep checking to be sure her gums are pink, that she is taking in liquids, and if you can take her temp with a thermometer, that her temp does not go over 103.
Let me know if this is helpful and what other questions you have.