Help my big Kitty please!?

I can't even imagine what would be wrong with your kitty. I wish I had a clue. When you said he won't close his mouth all the way, I thought maybe a dislocated jaw or something, but hard to say. I certainly hope it's nothing serious. Is he able to chew?

im not a cat expert but i think your cat might of ate something really bad, ate something sort of spikey, he might have a sore in his mouth that hurts when he eats so he's not eating that much and can close his mouth or he might be getting a little too old. i hope your cat starts to feel better.

You're cat is pretty old, so he may have hurt his hip so it hurts to jump. As for eating, he may have a sore on the roof of his mouth and it bugs him when he eats. Hopefully it's nothing too bad!

that happened to my dog and cat once. the dog ate a bee and got stung so he was fine but the cat had some kind of liver disease soo..i might be gum or liver disease

he may just be getting old

yeah take him to a vet

that's old for a cat.

Best of Luck

taking him to the best thing you can do