Kidney back pain is usually felt where the kidneys are located, which is just above the arches of your pelvis on either side of the lower back. It can also be felt in the front of the groin and hip area as shown in this diagram below (this is called referred pain and is where pain is felt a distance away from the cause).
This can be confusing as normal non-specific low back pain can also cause pain in the same areas. But there are usually clear differences between normal back pain and kidney pain. If I am assessing someone it is usually a combination of symptoms that would make me suspect kidney not lower back problems .
Kidney stones may be painless if they are small, if they are larger they can get wedged in the renal pelvis or ureter as the body tries to pass them, this may cause extreme pain. In addition stones can cause an infection leading to the same symptoms shown above.
In my practice I have very rarely come across someone with kidney back pain that has been mistaken for a lower back problem. You can usually tell the difference straight away.
Do you think your lower back pain is a kidney problem? The only way to be sure is to go and see your doctor who will be able to diagnose this either with a clinical examination or by organising some tests to check for infection or stones.
This is a nice 3D video showing you where the kidneys are (muscles start at about 3 mins)
A useful outline of kidney problems can be found on the NHS direct Web Site