Hi i have a 2.5 yr old bulldog who has been on frontline since she was a puppy and this past week when i gave it to her she had a terrible reaction. It sounds a lot like your dog. She first had a "greasy" looking spot where i had given her the frontline that showed up about 2 days after i gave it to her. i bathed her right away by that evening it was 3-4x as big and i could see the skin underneath was red, i bathed her again by the next morning it was bigger i took her to the vet they shaved