Firstly!
Forget the BM flea treatment!
You really need one of the prescription treatments available from the vets! You can also buy these online and they are a lot cheaper! but due to the tender age it is best to speak with you vet first as some preperations are not suitable under twelve weeks!
We go our last cat now fifteen when he was just 3 weeks old! (long story) he was wriggled in fleas so we washed him in the sink (not recommended) we have since used the frontline on him and believe he has remained free of these little blighters!
lol
DT