What Causes Stabbing Pain Below The Ribs?

I get sharp severe stabbing pains on my left side right below my rib cage. To the point where i cant talk and taking deep breaths while it is occuring make sit even worse i have to lay there clutching my side for about 45 seconds waiting on them to end. I cant tell when they are going to happen they just happen and there is nto really a pattern to them. Im a fifteen year old girl. Any ideas?