Karen,
I'm so sorry it didn't work for you. I think it's suppose to get longer releif each time although my neurologist stopped after the first series in my neck didn't last.
If you have a request for a certain treatment I believe the doc has to at least talk about it. The only thing I have to go by is when I speak to my neurologist about certain areas or symptoms she listens and examines that area but so far I've followed all of her advice. Being that it's our bodies, I would imagine that we should have the last say in what goes on.
Maybe after you tell your doc the block didn't work he/she will be willing to try the other area.
Remember the headaches I was getting in the middle of my brain? The Nortriptyline seems to be helping...