Something to Be Worried About?

I recently found a lump a little above my left hip, just left of my abs. It isn't very hard, and causes me no pain, but I still don't know whether or not to be worried. The thing is, I don't have a bump that corresponds with it on my right side, so that's what originally made me notice it. But i'm only fifteen. Is it possible for someone of my age to develop cancer out of the blue? I'm pretty healthy. My father passed away from liver cancer a few years ago, but I don't know if that has anything to do with it. Should I go to the doctor?