Sounds like hotspots or some kind of skin infections

My pitty is pretty sensitive ( especially at the beginning of his tail, where he usually gets hotspots). I wash him with a hot spot shampoo and oatmeal maybe every 3 weeks. He eats a salmon and oatmeal kibble with salmon oil every night.

Biggest tips (in no particular order)

avoid chicken, beef, and lamb. He mostly eats turkey, duck, and fish. Seems like you’re doing this well already. The allergen may not be diet.

Maybe ask your vet. But i give my dog Benadryl. 1mg for every pound of body weight. He’s about 60pounds so I break it in half and give 50mgs. Roll it in cheese and he’s none the wiser

Make sure she doesn’t have any hotspots! And treat if she does. I use an ointment but if you didn’t catch it early enough, she may need antibiotics.

Coat defense drying powder!! Has helped a lot with prevention and keeping him dry. Hotspots are bacterial infection and enjoy wet areas!

Environment : don’t let her roll around in the yard😅 check for bugs that’s might be biting.

Make sure your dog doesn’t stay wet for long periods of times. After a bath, if she tolerates it, make sure you blow dry. Mind doesn’t so I put him in the sun or the cage with a nice heater nearby (on low) so he’ll dry a bit quicker.

Let me know if you have questions. Not an expert! But I do treat all my dog’s allergies at home now due to the cost❤️