Rapid cat health degeneration, leads to Death?

Hi, I'm trying to find out more about why my favorite cat died 3 years ago after having to be put down.
So... I'm gonna list some things off:
When my cat was a kitten, it was healthy, excited, playful, and was healthy.

About 2 years later, the cat started to Constantly Eat. So we had to start covering the food bowl regularly otherwise the cat would eat until it would Vomit. When the food bowl was covered, the cat would walk around, and just lay down, and stopped playing at all. The cat wouldn't do much, it would just "Wander" around like it is trying to relearn its environment.

Eventually, it would vomit regularly, just out of no where. He would just start "Choking" on something and vomit; it eventually got to the point it was about 2 times a week.

Later, it lost the ability to use the litterbox, and would regularly go on the floor. We took him to the vet at that point, but I don't remember what they said.

Then when sent him to someone else to care for, and a month later the cat was put down.

Any ideas what would cause a cat to become ill / mentally degenerative after 2 years?

Do you still have any medical records from your vet? Could you call the vet and ask them what the diagnoses was? Most vets will keep records of their patients for at least three years so that would be the first place to look.

A virus that would cause a high fever that led to brain/organ damage could cause some of your symptoms. The problem is there are TOO many diagnoses that could cause this. I agree with the above, surely the vet has some idea what it was. It could have been some kind of inherited gene that lead to early death too. My heart goes out to you, that three years later you are still so full of pain and uncertainty. You gave him three years of caring and love, please let your happy memories give you comfort, not the memories of him being sick. Even the strongest heart quits beating in time, your precious boy left you way too early, but he left a piece of himself in your heart and soul. May you be blessed for helping him, and for loving him too. Take care of yourself.......