I run high school cross country and began having an achy, sore thigh one week ago. It began mildly painful but has escalated to extreme pain, especially while running. The most painful non running activities are sitting in a high up chair (it painfully stabs on one point in the back) and starting moving again after standing still. Also getting up in the morning is quite hard. Could this be a stress fracture or something more like a strain? All this has only happened in a week which confuses me. Thank you!!