Mychal, this is a lot to deal with! I will try my best until Connie has time to get back on here too! I have had several allergy dogs, and my current one is allergic to 45 different environmental things - it is very frustrating to try and dig through all this.
As far as the itching, have you done the white sheet test for fleas several times to make sure you really don't have any fleas? Even with using a topical, they can pick up a couple of fleas on walks, etc. and they can bite before they're dead - the topicals are not repellants so you can still have an occasional bite. I would do that test, looking for flea dirt. If you are positive you don't have a flea problem, then you can proceed to look at other things.
The staph and yeast infections are usually secondary to something else - i.e. allergies where the skin is getting scratched and bitten so yeast and bacteria can be introduced. Seborrhea is also sometimes a cause - an oily skin condition. But whatever the cause, the yeast will usually keep recurring if the reason isn't dealt with. To confirm yeast you need to get some scrapings done by the vet - I would recommend scrapings from between the toes, belly, ears, groin area, and where the dog seems to be greasy feeling. The vet can look under the microscope right there and tell you IF there is yeast, and how much, and where.
The thing regular vets, as opposed to dermatology vets, are NOT good at, is knowing WHY that yeast is there. They will usually blame it on food allergies and put you on some high priced hypoallergenic kibble that they sell. Not because they are bad vets, just because they aren't educated in skin very well. We spent bundles of money on exams, Rx's, tests, kibbles, etc at the regular vet and got no where fast. One trip to our derma vet and we were on the right path fast! They usually know just by looking at the dog, and where they are itching, what is going on. It doesn't mean you have to spend hundreds on skin testing and such if you chose not to. It just gives you a good evaluation to go on in deciding which direction to take.
The other thing it does is takes the stress off your shoulders! I got so tired to trying to figure things out all the time. One visit to the derma vet and we knew what our choices were. Kasey is highly sensitive to any yeast on his skin - just a tiny amount and he's itching like mad. So the derma vet has us give him an oral anti-yeast Rx every weekend for 2 days and he's been yeast free for years (we gave it for several weeks to clear him of the yeast first). It is often hard to irradicate yeast that is all over with baths only.
So I would highly recommend an eval by a good derma vet just so you know what you're deal with. I know this is already long, but I will post my derma vet info that I have learned below. As far as the shaking of the head, it may take a while after having the fox tail out for the 'feeling' that something is in there to go away - it has for Kasey in the past. And the Rx drops you are putting in there will make the ear oily - I hate that!
Here is the derma info:
1. Most people, and many vets, assume that if their dog is itchy, they should change their food - the kibble companies have brainwashed us into thinking that food allergies are very common in dogs, and so you should switch to an 'allergy-free' kibble if your dog is itching. The truth is, less than 10% of dogs have food allergies! And some breeds less than that - for example, it's less than 3% in golden retrievers. But food is the one easy thing that a regular vet can do to try and help the owner of an itchy dog - plus they make money off the 'hypoallergenic' dog kibble they carry.
2. By far, the most common allergies in dogs are flea and environmental. If your dog is itching a lot, the most important first step you can take is to make absolutely sure they have ZERO fleas! I was one of those people who thought we didn't have any fleas because I was always checking Kasey and never saw any. Wrong! One day I found one flea and that was enough to drive him to distraction. We started using flea treatments (which I hate to do, but the cycle of itching, biting and chewing, which leads to open sores and infection, was worse for him). Keeping him flea free has helped, but he also has environmental allergies, which is the next most common thing to check for.
3. Environmental allergies can range from anything like mold, pollen, grasses, etc. to even people dander! Yup, Kasey is allergic to me! Usually only a derma vet is knowledgeable enough to be able to do the required skin testing and reading of those tests to determine what the dogs are allergic to. Blood tests are a waste of money, both for food and environmental allergies - don't let your regular vet talk you into them, they are not an effective diagnostic tool. Skin testing IS more expensive (usually around $300 - $400), but it is very trustworthy.
4. If your dog is biting and scratching mostly on the back half of their body, fleas are highly suspected as the cause. If more the front half of the body, or the whole dog (especially paw chewing, ear infections/itching), suspect environmental and flea. Many dogs who have environmental allergies are also allergic to fleas.
I spent Kasey's second year of life going through a zillion different kibbles, home-cooked diets, and prescription dog foods - it was a big waste of money, time and anxiety trying to find the 'right' food. A year and a half ago we learned, from this site, how to feed raw and he has been healthier ever since. It didn't fix his allergies, but the derma vet believes the good nutrition has definitely kept his skin and coat in excellent condition in spite of his itching! I hope this info will help even one person who is struggling with the frustration and helpless feelings of having a dog that is constantly itchy! Going to the derma vet has taken all the guessing and responsibility off my shoulders, and that is worth the extra cost of a specialist!
(I would like to add that we would have ended up paying less in the long run if we would have gone to the derma vet first instead of trying all the other foods, drugs and trips to the regular vet!)