Looks like a yeast infection. I would go back to a grain free food. It can take a couple of months to really see improvement, as the allergens have to work their way out of their system. Many people switch the foods to quickly, and assume it didn't do any good because they don't see results within 2-3 weeks. Give it at minimum 3 months, unless the allergies become worse. Also, it may surprise you to know that they typical "safe" proteins like lamb are not. I've had several dogs that were allergic to lamb. I have a mastiff that gets diarrhea if fed chicken. I had another that was allergic to chicken, beef and lamb. He went on a salmon based diet and did wonderfully. The trick is to stay away from the "common" proteins like chicken, beef and lamb. Go with a grain free venison, rabbit, turkey, salmon or buffalo based food. Stick with one protein. No combos. I cannot stress grain free enough. Dogs don't need grains, and for dogs prone to yeast infections, the grains can make it worse as the carbs feed the yeast. Just because a food is high quality and expensive doesn't mean your dog won't be allergic to it. Also, when you switch, switch slowly. 75-25 ratio, with the 75% being the current food. Do that for at minimum 1 week. Then do a 50-50 ratio for a week. Then 25-75 a week, then completely switch. You have to give their bodies a chance to adjust to the changes. Also, medicated baths would help her immensely. You can order this from Jeffers or get something similar locally.
KetoHexidine Shampoo Another thing many people don't think about is the treats. If your dog has food allergies, then you have to be careful of the treats as well. We had 2 sets of treats in our home. One for the non-allergic dogs and one for the allergic dog.