I'm lost on flea medication. My cats recently started living with dogs that go outside for a bathroom and exercise and have gotten fleas. They've never had this issue in the past, but now they're getting pretty bad. One of my cats is a kitten and too young to get medication (she's 3-4 months old) and the other is full-grown. What would you suggest I give the kitten when she gets old enough and the older cat right now?