Diane
Your Dr. is right. Your children are being re-exposed to lice. Have you made sure there bedding is completely treated? Have you taken care of stuffed animals, putting them in a sealed plastic bag for two weeks, if you have carpets then you should really fumigate the house. All hats and jackets should be washed in hot water and dried in a hot dryer. When you give them treatments you really need to make sure that every nit is removed. I have found that RID works best. It took me three tries with my own long haired daughter to rid her of these nasty pests. We never had them again. good luck to you.