I Have Been Itching For Two Months And My Wife

I have been itching for two months and my wife on and off , my doctor told me it was scabies . He gave us a script for permetheten . That same day I noticed my 2 yr old scratching his neck and legs . All three of us rubbed in the cream from the neck down and left it on for 12 hrs , we washed all bed clothes and clothes . The day after we did the treatment was our worst day ever for itching . It has been two full days now and are atill madly itching , how do we know if we killed the infestation ? And is there anything else we need to do ? We also have a 7 yr old and a 12 yr old but they have not showed any signs .