My 12-year old cat Kramer, an orange tabby, has been exhibiting very odd behavior over the past week. He is normally an *extremely* outgoing and social cat -- loves attention. Since last week, he's taken to hiding under the bed. He lets me pet him and he purrs, and will eat food if I bring it to him. My vet (who makes house calls) came to see him and didn't see any outward signs of illness. He did both blood and urine tests, and both came back normal. After the vet left, Kramer laid in the litter box all night! This behavior hasn't been continuous - one day he seems to be back to his old normal self, and then the next day, back to hiding. Last night he came out from under the bed and jumped up - when I reached out to pet him, he let out a horrible meow and dove back under the bed. He did come out to eat this morning, was affectionate for a while, and is now hiding again. Since I have another cat (who Kramer loves), it's hard for me to determine if Kramer is really using the litter box during the day when I'm out. Has anyone experienced this kind of behavior before?? I'm worried!!!