Brown crusty substance on th back outside of one ear

Hello,

Im a new kitten owner, and i just got her 2weeks ago, shes roughly 3 months old. The other day i noticed while petting her there was something hard on the back outside of one of her ears. I took a closer look and its brown, hard. Came out of no where. She had ear mites before i adopted her and got treatment 2 days before i adopted her. Im taking her to the vet tomorrow, im not sure of im overeacting by thinking its mites or if its just something else. Shes squirmish and not fond of me touching the area but i managed to get a picture

If anyone can tell from the picture if i should keep her appointment or just find some cleaner at the store that would be amazingly helpful!

I would keep the appointment. Does she shake her head a lot? Does she scratch the area often? It could be ear mites or an ear infection. If it's ear mites and you haven't chosen a flea treatment yet Revolution treats ear mites along with fleas, heart worm and ticks. 

Louann Jude said:

I would keep the appointment. Does she shake her head a lot? Does she scratch the area often? It could be ear mites or an ear infection. If it's ear mites and you haven't chosen a flea treatment yet Revolution treats ear mites along with fleas, heart worm and ticks. 

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I haven't noticed that she shakes or scratches more often since I got her, awesome thank you so much for the recommendation! We go in this morning in about an hour or two

How did everything turn out?