You poor thing, I definately sympathise, it is horrible.
I was getting bad sciatic pain maybe two to three months ago, then I started walking with a friend, three times a week for an hour and a half. We would also stop and let the kids play at the playground for a bit to have a rest. It really really helped. I still get bad pain sometimes overnight and if I overdo it during the day, but if you are up to it and don't really exercise I do suggest a slow long walk every couple of days.