I haven't had a problem with coral yet...had a couple close calls though.
I always carry a bottle of meat tenderizer in my dive bag. It's good for jelly fish stings. The enzyme in it neutralizes the toxin. Don't know about coral scrapes though. I wouldn't recommend it though if you suspect it may be infected. It sounds very painful....ouch!
Makes me hurt thinking about it....LOL
I would agree that if the antibiotic cream doesn't help in a day or so....or at least see some improvement....see a Dr. before it gets out of hand.
Good luck and our best wishes for her speedy recovery!