I know you said that you've tried the pills, but have you tried capstar pills? I gave them to my cats and my dog, and the fleas fall right off. We even crated one of the cats and there was like forty fleas in the crate after an hour or so. We weren't sure if the cat had swallowed his pill, that's why we crated him. After that, we followed through with frontline. It does feel like a constant battle when fighting fleas though.