Was a skin scraping done? It's a simple procedure & the vet looks under a microscope of the sample to determine if it's bacterial, fungal or yeast.
Usually, stinky dogs are yeasty dogs (& there's usu an underlying problem)...what kind of food are you feeding?
Yeast feeds off & thrive on high starchy/ carb foods diet. Must eliminate all grains, sweet/ potatoes, carrots, also treats containing the above & molasses, etc.
They also have special RX shampoos. Malaseb is great, you can get it from your vet or here:
https://www.chewy.com/malaseb-medica...B&gclsrc=aw.ds
I have one very yeasty dog, it's triggered by her seasonal allergies & Malaseb worked great on her. I switched to raw food years ago & she has improved greatly...doesn't need allergy meds & no more itchy stinky yeast problems.
I haven't tried this but Amazon also sells special medicated shampoo (avoid shampoos w/ oatmeal):
https://www.amazon.com/SynergyLabs-V...QSQAMP8ZD8X27Q Chronically Itchy or Smelly Dog? It Could Be Yeast Infections