[Ellie May]

It may be yeast but that can make them quite itchy.
Have you tried just cleaning them?
If that doesn't work/it comes right back, she does need to see the vet.
If this is a new thing and she doesn't really get dirty ears, I'd just go to the vet now.

We use Chlorhexiderm Flush here for ear cleaner but there are lots of good ones. If you think it could be something besides yeast, you may want to hold off on using cleaners in case they do further damage or cause pain...