Grimble im in the same boat as you. Flexerl nocks me the hell out for hours at a shot.
I also have pinched nerves in my neck and back.
Out of the list of herbs you posted you bought the one that grabs my eyes
is the KAVA KAVA root.
A teaspoon steeped in hot water for 10 minutes will give you the effect your looking for.
But allas even with the Kava you will build a tolerance to it and need to increase the dossage. Idealy the best way to go at this is have a few diffrent herbs at your disposal, and rotate which ones you use to help stave off the tolerance monster.
You might want to talk to yur doctor about Ultram , Ultracet , Tramadol. There all the same thing just diffrent versions of it. it isnt a true pain killer in the sence of a narcotic. It is an intagonist,, which means it uses you body own natural pain killers .
It also is a mood inhancer do to the endorphines it releases. Ive been on it for over a year now. I take one in the am and it gets me through most of my day without an isue.
Good luck in you search for commfort...