Hey Stephanie,
I knew Holly would chime right in about the Diatomaceous Earth, but I thought I'd add to that.
The flea medication can actually take around a month to work. The thing is, the fleas still have a cycle. So, even if the live fleas are killed, you still have the eggs that will hatch, then those fleas, and that should be the end of it.
The fleas are not trying to get away from the medication. The medication is in the animals' blood, they can't get away. Its not really a localized thing.
Make sure you are vacuuming your little butt off. Vacuum 2 times a day and throw away the bags. YOu need to get all of the eggs sucked up and out of your house before they can hatch. When we were dealing with fleas, I would vacuum and put Diatomaceous Earth IN the chamber of the vacuum (its bagless). I would also top the stuff that I threw out in the garbage with DE so they couldn't crawl out of the garbage can.
Vacuuming is seriously one of the most effective things you can do to eliminate fleas. Also, I started giving everyone supplements to make their skin "stronger" and less sensitive to flea bites. They get Dreamcoat.
But, Holly is SO right about the Diatomaceous Earth. If I were you, I would get a bag right away and do it up. Its really truly worth it.