I'm sorry your cat is not acting like herself.
Cats will make this loud/deep cry before they vomit, because they feel sick, may have pain in their stomach, need to throw up, and this is how they express it. Due to your description of all her symptoms and general change in behavior, it's possible that your cat has ingested a toxic substance or other non-food item inside or outdoors, which is causing her gastrointestinal system to be upset.
An intestinal viral or bacterial infection is also possible, as are some other medical conditions. If your cat is not spayed, she could have developed a serious uterine infection called pyometra, which requires immediate veterinary treatment, but if she is spayed, we don't have to worry about that.http://www.sniksnak.com/cathealth/pyometra.html
It would be a good idea to have her evaluated in person as soon as possible, by a vet, so she can be diagnosed and treated, then feeling back to her normal and happy self.
I hope all will be well with your furry girl!
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