I'm sorry to hear this. I went through something similar but not as bad many years ago. I only had 2 cats at the time and they're both indoor only. They both got fleas so I took them to the vet and they got some kind of a shot so that the fleas would become sterile and wouldn't be able to multiply. I think it was a program shot but I don't think that they have these any more. They do have the liquid and pills though. Then I also bought some advantage and I put it on them. I've been using advantage every month now and I've never had another problem. I buy the large dog kind and then I measure it so I save money and it'll last me a long time. My vet approved this and recommended this to me. At the time I took my cats out and I sprayed my carpet and then we all left for a while until it was safe to return. Good luck.