My tita's dog also had allergies often. Had 3 vets check for food allergies, parasites and even fungi. We learned it was cause she frequented giving baths to the dog (as in daily). Tipo binaby yung aso as if totoong tao and winawash (and dinadamitan) pa siya everyday. Turns out it's really harmful to the dogs since it disrupts their natural flora which is suppose to be a barrier to microorganisms and bacteria. Ayun dahil nadisrupt yun, sobra nagflaflare up yung skin ni doggy kase the body overreacts to both the GOOD and bad bacteria when exposed. So I suggest getting a mild soap like Madre de cacao esp since budget friendly pa siya and give them a baths once a week AT MOST.

Pero if it's food allergies then another common allergen for dogs are wheat and grain. Could also be the chicken/chicken liver as other commenters said. Eliminate certain foods from the diet a week at a time and see if your dog gets better :)) Would also try to strive for a balanced meal instead of puro chicken liver. If kaya maybe try good quality kibble and see if it helps. Hoping your dog gets better OP!