I know we are trying to be natural here, but as you were already using flea bath (I think)? Try bathing them in dawn every 3 days and getting them completely dry afterwards. Or you can put some dawn with water in your hands and rub on them then rinse off. Blue Dawn only. It kills fleas, lice, ticks etc.... It's what they use on marine life in oil spills as well. Very safe and effective. It was recommended to me by my vet for 2 week old kittens we found in our basement covered in fleas and lice. Every 3 days for 2 weeks. By the time they were old enough for their 1st shots they were flea and lice free.