As far as I can opine on this, she might have got some kind of pox. This is highly infectious. Is it advised that you immediately take him to you vet and ask him to consult and check what you pet has been u with.

Hurry!

 The only thing I can think of is a flea infestation. Try examining your cat by turning her on her back if she'll let you and look very closely and see if you can see any blackish brown bugs scurrying around in her fur. You may also be able to see them on her face if her fur isn't dark. If she does have fleas you'll need to get some type of flea medication or collar for her quickly. If you don't and she's an outside cat that also comes into your house, you will have fleas in your house and they are difficult to get rid of. Good Luck!