I hope you and Cassidy are doing better today. In all my years as a registered vet tech, I know that eating and drinking is always a good thing. Also, please don't ever hesitate to take her to the Animal Emergency Clinic. I worked emergency and critical care for nearly 10 years, and I would always tell the owners that if they think something is wrong, don't hesitate to bring your pet in. It's always better (and a weight off of your shoulders) to be a little too careful. I can't tell you the number of people who said, "I'm so glad I came in" even if there was nothing really wrong with the animal.
Anyway, I will be thinking of you & Cassidy. 16 years is a long time, but you can't put a time limit on love. I always say that pets leave paw prints on your heart. Best wishes, and if you think you need to take her into the ER, then take her. BTW-if you are going to take her in, it's always a good idea to call the ER first. Sometimes the doctors are in the middle of a surgery or some other life threatening procedure. Also, if Cassidy takes a turn for the worse, it's always a good idea to call them to let them know you are on the way. That way everyone can be ready when you come in. Those few extra minutes could save her life.
OK, sorry for talking like a vet tech.
I'm just trying to give you some info. I really do hope that Cassidy feels better.