I am sorry to hear you are worried about Chamois. My name is Rebecca. I am a veterinarian and will do my best to help.
Please check her gums, and tell me if they look pink or pale in color.
Are you able to take her temperature at home with a thermometer?
Does Chamois go outside at all?
Vomiting in cats can be caused by many things: eating something they should not that is causing irritation to the stomach and intestines, infection, eating something that is causing an intestinal obstruction, parasites, injury. To tell if this is serious (obstruction) or not, I would need to be able to check her gum color, take her temp, palpate her internal organs and lymph nodes. She could spend the night resting and be back to normal in the morning, or if she ate something that is causing an obstruction, she could need medical attention.
If her gums are pink not pale, that is a good sign. If her rectal temp is between 101 and 102, that is also a good sign. Just let her rest for now and if she goes a few hours without vomiting try offering some broth or water to see if she will take it.
If you are really worried, I would consider taking her to your local veterinary emergency clinic, especially if her gums seem more pale than her litter mate's.
Let me know what other questions I can answer.