What it sounds like you are describing as occurring with Bailey is a problem with underlying allergies. This is usually what leads to the recurrences. Allergies can make a dog's skin itch and there may or may not be other skin lesions visible. Ear infections also stem from an underlying itch. Itching problems in pets can be difficult to diagnose and the history and response to medications tried are a very important part of figuring out the cause.
As far as the cause of the allergy, dogs can be allergic to three things: 1) fleas (different than a dog with fleas, these dogs are sensitive to even one flea bite), 2) Food (they develop antigens to some component in their food), or 3) inhalants like dust, pollen, molds, etc. On top of allergies, this affected skin can then be invaded by bacteria or yeast which can add to the itch, even if the original allergy has now subsided. When these bacteria or yeast live there for a long time, the skin can develop secondary lesions and even become blackened and thickened. Discolored nails can be a sign of yeast infections. In the ears, the allergy causes the ear canals to become inflammed and itch. These inflammed ears can then be invaded by bacteria or yeast which can add to the itch just like on the skin and cause the debris that you see. When present chronically, these bacteria or yeast changes can occur in the ear canals that make it harder to clear the problem up.
The key to getting these to stop recurring is to figure out if they recur because they are not treated completely or if it clears up and the allergy flares it up again. The first step is to insure that the right medication is used. A test called an ear cytology can be done to examine the debris look for secondary invaders like bacteria or yeast. Then your vet can determine the appropriate choice for what may be residing there. After treating the ears, it is ESSENTIAL that they are rechecked. A otoscopic exam of the entire ear canal to visualize normal canals and eardrum must be done to document that the ear infection has resolved. If this is not done and the signs recur, it may be that the ear was never treated completely to normal.
If the treated ear returns to normal and then there is a recurrence of the signs, then you know that there must be an underlying cause such as the allergies mentioned above. Your veterinarian can then work with you to determine what your pet may be allergic to and institute steps to control her response to the allergies.
With the skin, antihistamines are sometimes tried for control of the itch in allergies. It works for some pets, but not for all. It is usually not very effective when there is a bacterial or yeast infection present. Another thing that will sometimes help in mild cases is fish oil or omega 3 supplements. A test called a skin cytology can be done to look for secondary invaders like bacteria or yeast. There are other things to look for as well that can make a dog itch and cause skin changes like mange mites, ringworm. Sometimes we need to use corticosteroids to control the itch, but only after we make sure we have treated the secondary issues if they are involved as well.
It is very important to work with someone who understand allergies and can look at his history and seasonality of itchiness, results of dermatologic exam and response to medications and put it all together. I would schedule your dog for a physical exam including a thorough dermatologic evaluation with your veterinarian as soon as they can get her in. They will be able to best determine the appropriate medication to prescribe for her based on her current condition and help you to formulate a plan to prevent recurrences. Allergic dogs can be very difficult to manage, but with close communication between you and your veterinarian, you should be able to help her. Don't be afraid to get a second opinion or ask your vet for a referral to a veterinary dermatologist if you feel you are not making progress.
I hope this is helpful. Please let me know if you have ANY other questions. My goal is to give you 100% satisfaction and if you are not yet satisfied, please reply so I can clarify for you.
My posted replies are for general education only and not meant as a diagnosis. Only after a thorough veterinary examination can a diagnosis for your pet be made and specific treatments be advised or medications be prescribed.