::hugs:: Our old cat Mr. Wurm was 17 and started to just sleep more and act more listless so Sis took him to the Vet where they looked him all over and just gave him a shot to pep him up. Two weeks later he just lost interest in everything and she took him back. This time when the Vet felt him they paused, x-rayed him and he was filled with tumors. They didn't think he would have survived the surgery so we put him down.
He went from no tumors to masses of them in two weeks so evidently in someone that small a lot can happen in a very short time.
You just have to remember all the good times you had together and laugh about all the funny little things they did and not dwell on the fact that they are gone. If you believe in this sort of thing my Sis goes to a Psychic Fair every year and they have an animal psychic there. She talked to Mr. Wurm and he told her how grateful he was for being put to sleep because he was so sick. He said he wants to come back as a new pet and that he sent Sis's current cat to her. Make of it what you will.