Dog scratching one ear to point of hair loss

Question
I have an 8-month old mix [rescue dog] who seems increasingly tormented by a problem with her right ear. She does scratch, in general, more than she should and I have had her to the vet several times to address this, but the real focus of her attention seems to be that right ear. Some details:
- At the end of Nov, her ear was noticeably inflamed. I took her to the vet who confirmed the inflammation and, in lieu of any invasive scraping or swabbing, he gave me a medication of hydrocortisone and miconozole which I administered for 10 days. The inflammation subsided and a general mild improvement seemed to result.
- The general scratching on the rest of the body continued and this week, her ear began to bother her again - to the point that she'd stop multiple times during her walk to scratch it. She started to shake her head more.
- I took her back to the vet, thinking it might be yeast, as I detected a very, very MILD sour odor in her ears. The vet swabbed. Oddly enough, the dogs ears are PRISTINE and always have been. Besides the VERY MILD odor, there is no discharge or gunk at all. The vet could not get any visible stuff on the swab but swabbed anyway. All came back negative. The vet now wants to scrape to rule out mites. We both agree that mites are unlikely, but will scrape anyway.
- I noticed that the edge of her right ear has small, dry scabby flakes and she is losing hair on the top and underside of the ear. It now has half the hair of the other ear. There is no inflammation and her other ear is fine. Yesterday, however, something weird happened. Out of nowhere, her right EYE appeared to be smaller than her left. There was no noticeable swelling, but the eye was nearly closed and the inner 'white' of her eye was all red. I thought that she may have scratched her eye walking through some bushes. It cleared up over the course of the day. In the evening, when her eye looked normal, I gave her a lamb & rice stick. When she was done, she came up to me and her eye was shut again!
- We had suspected from the outset that she might have a food allergy that was causing the generalized itchiness and I started to eliminate obvious sources of wheat, but we have not begun a formal elimination diet.
- Oh and this is another odd thing: She is not tormented by this all day. Rather, it seems like she itches most when she wakes up in the morning and in the evening before she goes to bed. During the day, she plays, naps, walks and is usually okay. She just has this "bouts" of itching and scratching and that one ear is bearing the brunt of it. And again, all visible parts of the ear are very clean. She is not a floppy-ear dog and the inside is clean and dry.

I feel so bad for the little thing. I can only imagine how tormenting it is for her when the itching starts. I am praying that it's not a food allergy and would like to rule out something bacterial. Is there a medicine that I could ask the vet for that would address bacteria since we tried the miconazole for the fungal and the irritation returned? I suspect that the improvement was due to the hydrocortisone in that product and not the miconzole.

Thanks so much for your help.

Answer
If the ear responded to hydrocortisone, then ter probably is some type of allergy.  Allergic dogs will have re, hot, itchy ears and they may never have those ears get infected, just inflammed. Steroid tablets may help that.  If there is crust along the ear, I would skip the skin scrapings and do an insecticidal dip for sarcoptic mites anyway to rule that out as a cause of her misery. Skin scrapings are only about 50% sensitive.  If they found mites, then that tells tham they are there.  But if the scrapings are negative, the mites may be there and they missed them.