My Mother Had Severe Drumstick Allergy 40 Years Ago. She

my mother had severe drumstick allergy 40 years ago. she is 75 now.for last one year she has severe itching under the skin.it becomes very traumatic,she has to take steroids since anti histamine don't help. pl help. what foods should she avoid / are allergy tests of any help/ where r they best done?i live in ahmedabad.asha