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I am so sorry your dog is so sick. I am very concerned about her, and I do not think it is a good idea to wait until Monday to have her seen. I think it is a good idea to take her to the nearest emergency vet right now. The dark vomit, stools and urine are very worrisome. They may be dark because there is blood in them, or they may be dark due to a byproduct of kidney damage and tissue break down (myoglobin).
There are so many things that might be going on with her, it's not really possible to tell you exactly what it is. Since she has had previous issues with her stomach, I am concerned about pancreatitis.
Another concern is hemorrhagic gastroenteritis.
She may have an intestinal obstruction due to a foreign body, or any number of other illnesses. Given her age, illnesses like diabetes, cushings and hypothyroidism are less likely, but may need to be ruled out. And of course, something other than what I have mentioned may be going on.
BotXXXXX XXXXXne, it sounds like she is painful, and very sick. The longer you wait to have her seen, the worse she will get and the more expensive and difficult it will be to get her well again. Please consider having her seen right away, and let me know if I can be of further assistance. Good luck, I hope she feels better soon.