Hi Mark,
Given the intensity of the itch, has scabies been ruled out (by testing the efficacy of a miticide on symptoms)?
If yes, then the first thing I would try is a real food low starch diet, such as a commercial raw diet or a homemade one. As you may recall from the lectures, the response to real food tells us whether you are dealing with inflammation dysregulation or immune dysregulation.
Cushings + very hot skin + intense symptoms = a 'hot and excessive' condition, making me think of Damp Heat, inflammation dysregulation, and Si Miao San.
First, though, given the eosinophils, give the Minor Bupleurum a chance. It often doesn't work in many dogs unless teamed with Si Wu Tang. If the dog is actually Damp, though, the Si Wu Tang may be aggravating. This then is the value of trying a real food diet first of some type: it helps eliminate the chance of making things worse.
Lastly, if Apoquel helped A LOT but now not, then we might be looking at a secondary Wei Qi deficiency from the Apoquel. It happens frequently. The main symptom of that is deep recalcitrant pyoderma. Especially if the lesions are bleeding, then the first thing I would do is try Bu Yang Huan Wu Tang along with antibiotics. Once significant improvements are seen, it should become more apparent what the cause of the problem is, whether Inflammation or Immune Dysregulation
I hope that helps
Steve Marsden