I used to work for a doctor and almost everyone who was tested is either allergic or sensitive to milk. It causes inflammation in the body. I'm talking about pasteurized milk, not raw, but these days not too many people have a cow in their backyard anyway.
Dairy is the number one reason for ear infections. Eliminate it. No one needs milk. The dairy board has done an excellent marketing job to have you believe otherwise. It's simply not true.
Since she's been on antibiotics she will need to use a probiotic to restore her bowel flora. Somewhere between 70-80% of our immune system is located in the bowel area and antibiotics destroy good bacteria.
Reduce inflammation with essential fatty acids like fish oil, borage oil, black seed oil--doubles an antibiotic without causing damage but harder to find. Use the regular amount for a week or so then double up. Do this for about 3 months and then just take the regular amount daily. Just about everyone on the planet is deficient of good fats.
Of course this isn't medical advice but it's what I would do in her situtation. Research each of the topics and you will find your evidence quickly.
As one of the other Moms mentioned, wheat may be an issue too. Sugar will also cause the bad bacteria to grow even more so ideally should be completely avoided. Replace with fruits, apples & berries are more low sugar than pineapple.
Instead of antibiotics use Otitis media homeopathic ampules, 1 (under tongue) every 12 hours for a total of 3, will wipe out just about every ear infection. All three must be taken but pain will go away quicker. These are from the company Heel. You may need to order them from an overseas pharmacy. I don't think they're available in the US. I haven't found anything else that works comparably though.
In our family once we removed allergens, did a good detox and restored the bacteria we stopped having ear infections entirely. I used to use the ampules when flying but my ears don't swell up at all during flying now either.
Oh, and don't expect a medical doctor to either know this or back you up on it. This is not what they're taught in medical school. My doctor took many additional naturopathic courses to learn this stuff after realizing all her patients kept coming back and she wanted to heal them instead of having a repeat customer.