kitty amnesia?

My cat very suddenly became unrecognizeable yesterday. She's a sweet, happy little love bug named Midget who adores her big brother Barnaby (a younger male) and my husband and me. Both my cats are indoor and neutered, and both are fairly normal (for cats!). They play often and Barnaby often gets rough without Midget seeming to mind.

Yesterday, I ran out of my room when I heard strange noises. Midget was hissing and screaming at Barnaby the way she did when we first adopted her a year ago, bringing her into an unfamiliar home. There had been no sounds of a prior scuffle. Minutes before I had been playing with a new toy with Barnaby, and as far as I know he was still playing when this started.

She looked like she was having a little trouble standing, and just seemed a little wobbly for the rest of the day. She wasn't spooked, but she would prowl around looking for her brother so she could attack him. Whenever she sees Barnaby now, she makes a mad dash for him and howls and screams, and attacks him. I don't understand it. Barnaby seems half heartbroken and half worried about her, and has been spending his time watching her from high surfaces where she can't reach him. He can't even walk by the door without her coming after him like a hurricane.

We have Midget behind a baby gate with seperate food/water/litter...

What can bring on a sudden change like that? Is it possible that she had a stroke? Any advice or ideas would be helpful. Thank you so much.

She couldhave had something like a stroke, but it's not very likely. More likely would be that she saw a strange cat outside the window and (all cats may do this!) took it out - the territorial thing - on the first thing that moved indoors (could have been you instead of Barney!). They usually get over the behaviour in anywhere from an hour to a couple of days, but you could speed it up by putting a dab of vanilla extract (used in baking) on both their chins and tail bases, so they smell the same. Also try using some Feliway (a pheromone wall plug-in) which should help. The wobbling could just be her stressed out self, but if things don't improve in 1-2 days I'd take her to the vet for a check-up. I had a wobbly cat once - lasted a day or two, but she was 18 and probably did have a stroke... seemed spaced for a while, and had a little trouble with stairs.