Getting into the garbage can cause garbage gut, pancreatitis or if there were any non food items eaten or bones, then this can cause an obstruction of the bowel. Garbage gut can produce abdominal discomfort, diarrhea, vomiting, lethargy and can progress into shock.
I would try to see a vet today if you have no idea of what she ate from the garbage.
IF you can't see a vet, I would not give the dog anything to eat for at least twenty four hours but water should be supplied. Then try a bland diet of boiled chicken ans white rice. IF the dog refuses this or cannot hold it down she needs vet help.
I would check the dog for fever rectally. Normal body temp for dogs is 100 5 to 102.5. IF she has a fever near 104. seek vet help Check the gums for pinkness, if they are white or pale she needs immediate help.
Taking a temp. http://www.petplace.com/dogs/how-to-take-your-dog-s-temperature/page1.aspx
garbage gut http://www.petplace.com/dogs/garbage-toxicosis-garbage-gut/page1.aspx