could my dog have an ear infection?

Species: Dog

Age: 5

Sex/Neuter status: F - spayed

Breed: Newfoundland mix

Body weight: 100 lbs

History: has allergies - constantly scratching and chewing paws; mostly under control with benadryl

Clinical signs: My dog tends to get ear infections every few months; I'm told that her allergies make her more susceptible. The typical symptoms are scratching her ears and shaking her head. She's doing that now. BUT - when I clean her ears out with a cotton ball, the cotton ball comes out clean. Every other time she gets an ear infection, her ears are gunked up with brown stuff. So my question is - is it possible for her to have an ear infection without having any gunk in her ears?

She did whimper a little when I cleaned her ears out - so they're sensitive - but I don't know if that's a definite sign of an infection or if she has just made them tender by constantly scratching them.

Duration: 4 days

Your general location: Georgia, USA