Try "Adam's" spray. I believe they have a kind that you can spray around your house. It stinks to high-heaven but it usually works. We went through this once. Our dog came back from the kennel with fleas .... even though he was on frontline
The Adam's worked quickly.
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“All his life he tried to be a good person. Many times, however, he failed.
For after all, he was only human. He wasn't a dog.”
― Charles M. Schultz
Warning: The above post may be dripping in sarcasm and full of smartassedness.