I have a chiwahwah and see was ill I took her to the vet a week ago she was running a fever and very dehydrated he gave her a shot and later that night she was running around like normal for the next few days she was like her self playing and eating. Now she is right back to not eating she is not running a fever I don't know what to do?

Take her back to the vet. Now!

I think you should go back to the vet with her

I have an extensive discussion of dogs not eating at https://www.askmehelpdesk.com/dogs/i...tml#post254171
It starts with a sick dog needing to see a vet.

The problem could be reoccurring, or a new problem. Don't put off or you may be paying an arm and a leg for weekend rates.