So, regarding your other post about "Liver Treatment", here's my input.
Since I assume you still don't have a real diagnosis, getting a liver support like Denamarin (Denamarin: Liver Medication For Dogs & Cats, Pet Liver Medication - 1800PetMeds
) can only help. Without a diagnosis, no one knows if it will help but it won't hurt. My cat with hepatic lipidosis was on it and so was my dog prior to and following her surgery for her liver cancer. Once her blood levels were near normal a few months post-op, I took her off of it. I've seen dogs with liver changes related to seizure medications do miraculously well on it. I think it's worth a shot.
Try the "special food" (If it's Hill's L/D, one of the few liver diets I'm aware of, most dogs hate the taste and won't eat it). If she does NOT eat in the next day or two, cook her some boiled chicken and rice. If she were mine, I'd be cooking that tonight just in case. She needs to eat in order to have any strength to try to repair whatever is wrong with her. Special food is useless if she won't eat at all. If she gets her appetite back, you can try adding some of the special food in but it's more important for her to eat given her weak state than not.
What Pawz mentioned is true. We'd have owners come all the time to feed their dogs-- often times they'd bring cooked food as well. It often helped.
I'd HIGHLY consider getting her to the specialist asap for the ultrasound and additional testing. I would not be waiting until Tuesday with a dog who is vomiting, losing weight and (potentially) is not eating. And, I personally would not be going back to that vet.