Hi, my short-haired cat developed a bald patch right in front of his ear last year. It went away after a while and didn't seem to bother him so I didnt' think anything of it. Well about 3 months later, he got another bald patch on the front of his leg that wouldn't go away and he scratched it constantly and made it bleed. I went to the vet and guess what? He had ringworm! So check your cat's skin for redness or anything that resembles a scab--if the bald patch doesn't go away soon, get her to the vet! Good luck!