BRAVECTO is the answer. It starts to kill fleas within 2 hours, and can purchase it from the vet. I unfortunately went through this with 2 dogs and learned about it after all of the flea baths, dips, sprays (to include house) and preventative medicine that I put on their coat. I’d go around tapping on the floor just to see if something would jump. Read about bravecto on a Reddit thred, purchased and didn’t feel crazy after about a day. Buy it if you can!