What's wrong with my dog?

The other day I noticed she had a wound on the side of her face near her ear. I figured mabey she got it from itching. But now it has gotten a lot worse. Its fleshy and raw, it looks like a flesh eating disease. She has been sleeping all day for the past two days which is not like her. She's only 2 and im really worried about her. I can tell something deffinatly isn't right. She has an appointment tomorrow morning and the vet said they were gonna keep her all day. Im really nervous ann anxious to find out what's wrong with her. Anybody have any ideas of what it could be????