Hello there. My name isXXXXX and I am sorry to hear about the kittens. The best thing to do is bath them completely with a dish soap such as Dawn. This cuts the oil that is on the skin that distributes the topical flea treatment throughout the skin. So spot bathing helps but the whole kitten should be bathed very well with a dish soap such as dawn. Monitor them closely as long as the shaking does not get worse they will improve with time. But if the shaking gets worse then there is nothing you can do at home and they have to be seen at an emergency hospital even if its far away because they will require strong drugs to reverse these effects of the flea medications. But hopefully washing them quick enough with a soap that cuts grease (oil) will help slow and/or stop the reaction. If the shaking gets worse we call this "shake and bake" because their internal temperature gets dangerously high and it can cause internal organ and brain damage. That is why aggressive treatment at the hospital is necessary if they worsen.
I hope that makes sense. Please let me know if you have any additional questions or concerns. I would be happy to help. Please do not forget to rate my response so I receive credit for my time. Thank you