Cat throwing up, potential fever, not purring

My cat 11 years old female has thrown up 4 times within an hour. First was about the size of my palm, second was about the size of a pen, 3rd and 4th was very little and almost like water in consistency. About 10 minutes later we felt her head and ears and all three were warmer than normal. She also has stoped purring, which is extremely abnormal for her, she's always purring, especially when both me and my mom are sitting with her, but now she's just silent. About 10 more minutes later the top of her head and one ear have cooled down, one ear is still warm. She definitely did not get into anything. She's dosent eat anything that isn't her food, not even tuna can tempt her. The only thing we could think of is the water that her and my dog share hasn't been changed since last night, we usually change it morning and night but not today. She's also an indoor cat.

Hello!  Older cats' can vomit for a number of reasons and eating / drinking inappropriate food and water is certainly on the list.   However, a range of systemic diseases such as liver disease, diabetes, kidney disease, internal infections (peritonitis), pancreatitis, cancer and also foreign bodies etc are on the list too. Cats that are losing fluid through regular vomiting are often unable to replenish their fluid levels by drinking alone and it makes sense to let her vet examine her in case she is dehydrated, especially given that she is unwell in herself.  It is unusual for a drinking water set-up that has worked thus far, suddenly to cause a problem and because of your cats' age, your vet may ask to run tests for some of the other causes and give her a good look over. Best of luck and please let us know how you get on.

On an urgency scale, it is important to let your vet triage her case as they may decide to see her today.