I have not heard back from you but did want to leave my thoughts about what you have told me thus far.
Now if she is wobbly and weak, we do need to tread with care. This could be triggered by her self starvation secondary to an infection but it could also be a sign she has eaten something she should not have. If you think there is anything harmful she could have had, then we'd want her seen urgently.
Otherwise, if that can be excluded, then we'd be worried that the signs she is showing is related to a low blood sugar from not eating. To try to address that, you can try rubbing a sugary syrup on her gums to give her a boost. Examples we can use include glucose or karo syrup but also honey or pancake syrup can be used in a pinch to give her a sugar boost and hopefully reduce these signs.
Afterwards, we need to tempt her to eat as we monitor her. Favorites are allowed or we can try an easily digestible diet option like boiled chicken, boiled white fish, or meat baby food (as long as its garlic/onion free). There are also OTC vet diets that can be used (ie Hill’s I/D or Royal Canin’s sensitivity) too. The aim of these diets is that they will be better tolerated/absorbed by the compromised gut. Therefore, it should get more nutrients in and result in less GI upset.
Though if she cannot be tempted but isn't vomiting, we can also syringe feed. We can use a calorie rich diet like Hill's A/D, Royal Canin Recovery or even the meat baby food. As well, there are also liquid diets like Clinicare Canine/Feline Liquid Diet or Catsure. All of these are nutrient dense, so a little goes a long way nutrition-wise. And these could just help get some more calories in even if we can’t get a huge volume of food in.
As well, dehydration is a risk and thus we'd want to monitor her hydration. To check that she isn't dehydrated, there are a few things you can test. Further to checking for gum moisture, do make sure she doesn’t have sunken eyes and that she doesn’t have a "skin tent" when you lift the skin. To see how to check these parameters for dehydration, you can find a good video HERE (http://www.ehow.com/video_12232503_dog-dehydrated.html). If you are seeing any signs of dehydration already, then that would be our cue to have her seen before this becomes an additional issue for her (especially as it is often dehydration that makes them feel unwell).
Finally, if you suspect she is nauseous, then you can also try her with a low dose of an OTC antacid like Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid), or Tagamet (More Info/Dose Here @ http://www.petplace.com/article/drug-library/library/over-the-counter/cimetidine-hcl-tagamet). Whichever you choose, we’d give this 20 minutes before food to allow absorption. Of course, do double check with your vet if she has a known health issues or is on any medications you haven't mentioned. Though if she cannot keep that down, then we'd want her local vet to treat her with injectable anti-nausea medication.
Overall, there are a wide range of agents could trigger what we are seeing but with her being so young we need to be very careful. Therefore, as long as we don't have a toxicity risk, we’d want to start supportive care to settle her stomach. If she cannot keep that or water down at any point, appears dehydrated already, or doesn’t respond to the above within a few hours (since she is little); then we'd want to get her vet involved. They can assess her hydration, rule out fever, make sure there is nothing in her stomach that shouldn't be there or any sinister viruses present. Depending on their findings, her vet can treat her with injectable anti-vomiting medication, fluids, appetite stimulants, +/- antibiotics to settle her stomach, and get her back feeling like herself.
All the best,
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