My fiance and I just recently rescued a one yer old American Bulldog/Pit mix. She went to the vet on Saturday for a check up. She was given lymes vac, bortadella vac, and cortisol (spelling?) for her skin allergies. We are changing her diet to Nutro. We gave her a bath on Sunday and lastnight we applied Advantix. Around dinner time today, we noticed that she started developing big welts on her back, up to her neck. Pretty much the spots we applied the Advantix. She does occasionally bite at them, as it is irritating, but hardly at all. I know this sounds like the culprit but we can't get to the vet until next week. Any insight would be helpful.