Hi Nina,

one of the simple herbs for the kidney is Parsley. You can make a parsley tea and it will make you urinate a lot, so use only during the day. Start with a very small amount, only half a cup of the tea. Use about a teaspoon of the herb and 8 oz of boiling water poured over it. Don't let steep too long, or it gets bitter. Dandeliion tea helps both kidney and liver, and so does Burdock, a vegetable used in Chinese cooking. It's mostly used in soups. Eating Asparagus is very good for the kidney, but if you don't have enough magnesium in your diet, you could notice a kidney stone. Since you already have pain in that area, I would try the Dandelion, Burdock, Parsley. Many people on this forum talk about magnesium, so you will want to try taking some of that.
The herb we use here in the States to help dissolve Kidney stones is Hydrangea Root. Another herb is called Gravel Root, but I'm not familiar with the action of that herb. Using food, you could juice lemon and add it to water, that helps dissolve kidney stones also. These herbs are all naturally high in potassium, and you might be eating too much salt. So pay attention to that. Also fruits are high in potassium, which helps the kidneys, like Kiwi fruit, watermelon, and yes I know, bananas. Yogurt is also hi in potassium, but you already mentioned that sometimes your kidney is painful when you eat whey protein. Maybe you are like me and don't tolerate dairy products from cows. Try dairy products from goats. I use goat yogurt and goat butter.
Of course circulation to the kidney might be part of the problem, and all circulation issues can be helped by capsicum, which is cayenne pepper, and Hawthorne Berries.
I hope this helps you,
Joanne