Have you taken her to a vet? I hate to say this, but it just may be getting close to her time. 19 is incredible, and you must have done a great job to give her such a long life.
An older cat does slow down on eating, but what you describe could be symptoms of cancer or just old age. Do take her to a vet if you can afford too. You don't want her to be in pain, and it is possible it's treatable.
I had a 20 year old cat that just passed away in July. He had CRF (Chronic Renal Failure). He had those same symptoms and I took him to the vet. He was just 17 or 18 at the time. With the proper food and and fluids she can live for quite awhile if this is what she has. We had to give Morris an IV bag and medicine when it first happened but then he got better and lived medicine free for about a year and a half. After that we did give him an IV bag once every three days. They adjust very fast and it's not as hard as it sounds. The fluids make them comfortable. Good luck! Keep us posted.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.