Veterinary questions? Ask a Vet for Answers ASAP
I am sorry your cat is unwell and it is a concern that she is now vomiting as well as having diarrhoea. This could present the risk of her becoming dehydrated which is potentially life threatening. I would be encouraging you to seek veterinary attention, your vet even if closed will have access to 24 hour emergency veterinary services so they should be contacted.
My concern is that the recent ingestion of a mouse my be causing a serious intestinal upset, or even worse a blockage which could require surgery.
The absence of drinking and with the recent vomiting will increase the risk of dehydration.
If you are unable get her seen by a vet this evening, then you should offer her small frequent amounts of water to help it stay down. Starve her for 24 hours (her anorexia is doing this anyway) and keep her warm and comfortable until you vets opens in the morning (if not open there are other vets that are open on Sundays that won't charge an extra out of hour)
I wil continue writing so you have chance to read this
There are other causes of diarrhoea and vomiting that aren't related gastrointestinal disease, we sometimes see this with hormonal conditions such as hyperthyroidism but this doesn't often develop suddenly and is more likely in older cats. Sometimes heart conditions can also cause diarrhoea and illness, but again I would expect your cat to have been unwell for sometime.
So, to recap, she does sound unwell and I am concerned that if left in this condition she may deteriorate more and require much more invasive treatment (hospitalisation, fluids etc)
I really hope she is OK and it isn't anything too serious
Excellent, good luck