I can't stress enough how important it is to get her veterinary care! I don't understand why your mom doesn't seem to understand that!! If it were your pom she'd bring her to the vet, wouldn't she.... anyway I know this is in no way your fault at all, just keep an eye on it, make sure there is no swelling or green puss, or puss at all. Clean it daily.

What I'm thinking is that there was no padding on the bottom of her crate or cage or dog house and the hard flooring could wear the fur and skin down. But the picture you have is VERY hard to tell since its so blurry