Yeah, that is a very common location for a stress fracture. It's also quite possible that it's peroneal tendinitis (I had that too), but you can't be sure till you get x-rays and the doctor tests the severity of it. A stress fracture may not show up on x-ray, but the pain pattern will be a bit different between tendinitis and a fracture. See a doctor. If you cannot stand to walk on it, that's not good at all. You don't want to be making it worse putting off treatment.