if she had fleas at any point in her life then they're tape worms. to be honest in my experience the natural stuff never really keeps them away. for prob $15 you can go to a vet and get drontal, and it gets rid of them all the first shot.
preventative for tape (if thats what she has) would be some kind of anti flea/tick thing. frontline is expensive, and most of the otc things are crap. but frontline does work, and it works really well if you give them garlic with some of their meals.
as a sidenote, get that puppy to see all types of people, animals, and places. 7 weeks is awful young and if you don't socialize it, its going to be fear aggressive when it gets older. also be sure to spay her..haha