I'm so sorry Mingka is exhibiting these symptoms and has you worried.
For the moment, you can rub a couple of drops of honey, corn syrup or pancake syrup into her gums, as she must be hypoglycemic (low blood sugar) if she hasn't been eating well. She's probably dehydrated, too, if she's not drinking properly, so you can try to get her to lap up some water from a can of regular tuna (for humans, not tuna flavored cat food). Finger feeding her some plain, jarred baby food chicken or turkey containing NO onion or garlic products, is also a good idea, to get some nutrition into her. Beechnut Stage 1 Chicken is a good one.
With older cats there are many possibilities for weight loss and if she spends time outside hunting, and eating her prey, that can be dangerous if she ate a mouse who had eaten rat poison, because then, she would be 'poisoned by proxy'. Most rat poison contains a substance that prevents the blood from clotting, that's why it's so dangerous to cats or other critters that eat rodents.
Medical conditions more prevalent in senior cats are diabetes, liver disease, hyperthyroidism and kidney disease. If she can hardly eat or drink, lost so much weight over a short period of time and is almost too weak to stand, she needs to be evaluated in person by a vet, asap so you can find out a diagnosis and then she'll be treated. Sometimes, the vet will be able to get her back on track with medications and/or supplements and dietary changes, but it depends what is found, after some blood work.
At this time, from what you describe, it's sounds quite critical and not something you can treat at home, because you don't know what's causing the problem, so if you can get her to an ER vet tonight, that would be great!
I hope all will be well with your Mingka!
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