| you said she's spayed so it's a possibility for the weight gain. (or so that's been a common thing among other cat owners i noticed) Also, female cats seem to be emotionally independant more so than male cats so when they do become unusually affectionate, it can catch you off guard.
my female cat has always been a bit crazy too so random change in personality is nothing new for her. Sometimes i think she's playing behavioural experiements on me. Mine tries various ways to notify me she wants to play, be petted, hungry or wants to go for a walk outside. They even practice different pitches of "meow" to see which one piques your interest when one type of meow doesn't get you to do what they want.
Maybe she's using this new found method to get your attention for any of the above.
Or if you're cat is exceptionally tempermental, perhaps she senses a cat has moved in next door and wants reassurance that you love her. Some cats even trip out over something as simple as rainy weather.
A vet will ask if any change in cat behaviour:
have you changed her food?
has anything changed in the house?(moving around furniture, her food, her litterbox, new furniture)
any new pets?
new people moving in(aside from regular visitors)?
Any changes to her routines?(not going outside as often anymore)
be most cautious if she starts acting funny around the kitty litter box, if she's squatting or peeing strangely and starts making loud "meowls" consistantly, that is a potential emergency. | 
Linear Mode
