My cat has a patch of fur missing on the end of her right ear. She recently got over cat pimples on her chin (huge blackhead type-things) She's 10 years old and still quite active. I seen another post similar to this situation where the cat was pregnant. My cat is not pregnant. Her cat also had it on both ears, my cat has it on one. She's also kind of sensitive with it, I can't touch it without her growling. Stress could be it, I have a younger cat who terrorizes her all the time. I won't have money to take her to the vet for a while, But I will eventually, She needs her shots and she needs to be checked for kitty leukemia. My other cat needs to have his shots too. I don't know how to put a picture up.