What Causes Discomfort Around Kidney Area?

In recent months, I ve noticed a slight, dull throbbing discomfort which I believe to be in the left kidney area. Pain is too strong a word and it s isolated in a very small 2 square area - neither do I have any of the published symptoms of either kidney disease/failure. It s more noticeable on occasions, but no consistency to the discomfort. If I press on the area, the discomfort subsides....any ideas?