[Patricia A]

Get her off the flea/tick . Make sure there is no cleaners on floors or carpets that could cause reaction. Go natural. Wash body/paws if you do pesticides on your lawn after applying. Next SLOWLY, SLOWLY change her food. A little boiled chicken and string beans maybe mixed in with VERY LITTLE of a new kibble until she gets used to.
Give oatmeal/aloe shampoo baths with no PERFUMES/scents added to soothe skin.
Hope she feels better.