I second about the food. I had very similar issues with my shiba puppy- insane scratching/itching, ear infections, bad diarrhea. I swapped over all her food and treats immediately because I was tired of bringing her to the vet and not a whole lot being done other than spending my money. At my wits end, I stopped giving her anything with chicken, turkey, beef, grains. Here's what I feed her that made 100% difference. Within 1-2 months she no longer itches, has no ear infections, and potties well.

The Victor foods seem to all have beef and chicken fat/meals, ect in them. Good luck! I hope something helps your pup :)

Food: Taste of the Wild Pacific Stream for puppies( they make adult food too) https://www.chewy.com/taste-wild-pacific-stream-puppy/dp/181326

Treats: Natural Balance https://www.amazon.com/gp/product/B0793JSXSV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1Old Mother Hubbard https://www.chewy.com/old-mother-hubbard-mini-pick-patch/dp/176828

Oil once a day: Grizzly (the first first oil i tried, had beef in it too....) https://www.amazon.com/gp/product/B074N4XWVQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1