We were all of the sudden having flea problems too a couple of weeks ago. I hadn't had problems in yrs. I treated the dogs and cat, but also went out and bought some electronic devices that plug in to the wall that deter rodents and pests - including fleas - they admit sounds that only those creatures can hear -- I had these in the past, but I think the ones I was using aged out like smoke detectors do.
It's amazing the fleas seemed to have disappeared
