What kind of flea treatment do you use? Most of the ones from the stores do not work (in the US anyways) we use frontline or frontline plus and we get it directly from our vet. Daisy had a problem with that not working at first, so they ended up using the next dosing size, for dogs 22lbs (mind you she's not even 5lbs)
So it may be the treatment not working into the dogs body. Flea eggs are white (I believe) the black you see around it would be flea dirt (poop, which is dried blood really)
Keep the floors vacuumed well (every day) and you can sprinkle 20 mule team borax on the floors, and leave it for awhile before vacuuming. It's a laundry detergent, sort of. It's in that department of the store anyways.
Also, Zanny is right, make sure it wasn't a tick