Hi all, it's me again, I forgot to ask something else about my kitties - they've both been treated with advantage flea thingy, but as of like 2 days ago they've both been scratching at their necks quite often, and very hard. I'm not adding any flea medicine, I don't see any on them or around. What else could be making them itch like that?? I've checked their skin around their necks and there's no bumps or anything..... Thanks!