I'm sitting here with heated neck wrap around my neck, and my Tens Unit on my lower back. When I received it from my PT, he told me to use it no more than 20minutes at a time on one place.Is the purpose of it to stimulate the nerves so they don't hurt when you quit using it, or is it to block the pain while it is buzzing along? So far all it's doing for me is sharp electrical jabs that's making my back hurt worse. Maybe I'm using it wrong. Any ideas? I'm through with PT, so can't ask the therapist. I would just like to get some type of life back.