I have a pain under my right rib cage that hurts when I take deep breaths. What is it?

I am 14 years old and healthy. A few hours ago, I got up from watching TV for about an hour. When I did, I took a deep breath and I felt a very sharp cramp-like pain under my right rib cage. I haven't done anything strenuous recently so I don't think that it could be that. But, I have just begun gym cl after a "lazy summer". Could that be whats causing it? I'm really nervous. I have a "fear" of the doctor, really, I do. Please help!!!