My cat is not eating

Hello,  I have 2 cats that are 3 years old.  They were raised by hand from the age of 3 weeks when their mother was hit on the road (stray).  Starting on Wednesday both of our cats started not eating.  We took them to the vet on Thursday and were told that nothing was physically wrong with them.  Leo started eating again yesterday when we bought a new brand of food, he is now eating like there was never anything wrong.  Charlotte however is still refusing to eat anything.  We have tried a new bag of our regular food, the new food that her brother is eating, wet food, the food that my mom's cats eat, the kitten food that my mom's foster cats are eating and even crushing the food.  I have no idea what is going on.  She acts like she is hungry, running to her food bowl.  She sniffs the food that is offered and then walks away. She is being extra needy in wanting attention and does not act sick at all.  She is drinking water but will not take sugar water. any and all thoughts are appreciated!

I would try some canned food.  Or, you can try plain boiled chicken.  Keep an eye on her, too.  She needs to eat something soon.  She could need to pass a hairball or she might have an obstruction.  Is she pooping?

I will try the chicken, however she has never been a cat to have even the slightest interest in human food.  We have tried wet canned food and she didn't want it.  I am not sure if she is pooping because she shares her litter boxes with her brother, someone is pooping. I am pretty much ready to force feed her. 

Good news, my cat has started eating again.  Not up to normal but about 75%

Great news!  I know you're relieved.