UPDATE: That FB group was closed last night for a short while, but they're open again. Assbutts.
There's another group at Facebook whose owner is posting fanart without crediting the artists. If it bothers you as much as it does me, go take a look and help try to get them stopped.
Here's the link to the group's
main page. You might want to look through the photos there to see if she's posted any of your stuff without credit.