I have some cramping in my right kidney, what could it be?

I have a history of kidney stones, along with a kidney infection. My urologist sais that I have scar tissue on my kidney from it streching so much with the infection. Latley I have been experiencing some kidney cramping that comes and goes. The pain isn't crutial but it's enough to be noticed. I have consulted with my dr. and he seems to have no concern what so ever. Is it time to get a second oppinion or is he right? What could this kidney cramping be from?