If she has kittens she might be feeling sick due to a lack of certain nutrients, she might also be suffering from a uterine infection if she is not spayed, she could have parasites such as worms or coccidia or giardia making her feel too ill to eat, and she might have a giant hairball blocking her too.
The fact she is not eating is dangerous for her as cats who don't eat can get liver problems from prolonged starvation. If she isn't drinking or eating and not holding things down if she tries she may already be dehydrated and need fluids.
Your best bet is to get her to a vet and have them check her over to see what is wrong. An in person exam with a check of temperature and for parasites or for other signs of illness should help you figure out what needs to be done.
Hope this helps you!
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