My daughter got lice from sharing a school locker in elementary school. After I found out the other child was sent home with lice, I started checking but it was too late...all three of my kids had lice. I called the pediatrician and they ordered a prescription lice shampoo which I used and I also went through their hair myself, picking out the nits. It took me about 45 minutes per child and I did this twice a day. Of course all the bedding was washed in hot water and there is a furniture spray that I bought and I sprayed all the furniture.
Well, the lice kept coming back and I was slowly losing my mind! It turns out they can live on stuffed animals and all my kids had a bazillion of them. Once I threw out the stuffed animals and de-liced things for the one millionth time, we never had a problem again.
I'm sorry you are having to deal with this. If you are anything like me, it's driving you bonkers. But, you will get it under control.
Sherrine