One of the earlier books on herbs that I had read was by Jethro Kloss and called Back to Eden. He ran a health clinic and used water therapy, herbs and diet to heal people. You are probably familiar with Kloss' works.
Kloss had a remedy for dissolving and expelling kidney stones which was to make parsley tea. Boil some water, throw in some chopped parsley, cover and steep. Drink while warm.
The other remedy for clearing kidney pain is the use of watermelon. Make a tea from the green rind. I made and used this tea myself and it worked like a charm.