There is a lot to unpack here. First off, cats are creaatures of habit and territorial as well as social. So moving to another location is always very stressful and can cause illness as stress is obviously not that great for the immune system.
This young Lady now is in unfamiliar territory and there are no friends there - not saying you aren't friendly, but she doesn't know that yet, to her she has no one to communicate and huddle with for comfort.
Ideal situation is that you adopt a cat, give her a quiet room (yes, only one) to stay in until she eats & uses the toilet and then start making friendly contact.
Not eating or drinking for cats is dangerous, but I would wait with a vet visit as thats even more stress and won't help right now unless there are actual symptoms (eye discharge, sneezing, vomiting etc. - and yes not eating is usually a symptom as well but not immediately after moving territories).
I do have to say: please stop pulling her out of her hiding spot, wrapping her in a blanket or anything like that. It takes any sense of safety she had in her hidey hole away from her. It might very well be that she was shaking in your arms because she thought you were going to hurt her.
That being said, lets look forward instead of back :) So, the plan!
- Confine her to one room. Preferably it should be the one she is already in right now, but if that room is very well frequented all day, do move her only this one more time.
- In that room, offer her some boxes or blanket-caves/forts that she can hide in. Never reach into these hiding places. They are basically sacred for now :)
- Put a cat banquet into the room. This means loads of bowls (use soup plates if you don't have enough) with wet food, dry food, wet food with sauce, lactose-free milk, maybe some raw fish or chicken, cooked chicken (no bones, only a pinch of salt in the broth), cream, dreamies, anything you can think of. This is because yes, she has to eat, after three days of not eating aything a cat's organs start to deteriorate. So it doesn't matter if what she eats is crap, you can always get her used to some good wet food (at most 5% of grain/rice/potatoes/whatnot as thats just filler, rest should be meat and good entrails so not too much lung or udder tissue for example).
- Leave her completely alone. This is hard, I know. All you want to do is soothe her, show her you are a great person :) Unfortunately, that usually does the opposite, confirming for the cat that something has to be wrong if the big people also seem all worried and odd. Give her time. Only enter the room for the food, at most three times a day.
- Whenever you enter the room, don't stare as that can be perceived as an agressive warning. Just ignore her, maybe talk to yourself in a happy voice, just about what you're doing or whatever comes to mind. If she is out of her hiding spot, slowly blink at her if you want, but do not go towards her or stretch your hand out or anything. We want her to focus on calming down and food right now, not on you.
In the meantime, you can busy yourself and look up a bit about how to 'properly' (sounds weird, I know) pet a cat and how to read cat body language. Most cats for example are annoyed when we just pet them without 'asking' first. Asking in this case means holding out your hand and the cat rubs against it, incidentally also showing you how you should continue petting her. :)
And, as a last but still very important thing: This cat has lived together with other cats, she is social, cats are social beings in general. Please consider adopting another cat of the same age, gender and activity level&play behavior&character. (This after she has adjusted to you, maybe a month or so) Look into slow introductions of cats with protective gates etc.
