Welcome to HCM.
Your symptoms definitely suggest of allergic reaction
but a delayed one as you are having these reactions since ten days. This kind of reaction occurs in delayed type of hypersensitivity(allergy). It does not seem to be food allergy
. More likely to be contact allergy
. You have not mentioned your dogs hygiene. Is there a possibility it could be infested with any parasitic infection
. You might be developing allergy to the parasitic infection. Observe your dog for any lice or tick infestation. You could apply local calamine
on the rash and take Tab Allegra 120 mg after consultation with your GP.