What Causes Pain In Upper Leg After An Injury?

im 38, female, 5"3. Had accident 4 years ago, done damage to my upper left leg. Every few months pain comes and last for about a week then goes away. I dont feel sick, i train 4 times a week without any pain. I have had MRI, CT scan and now i am going for bone scan? What does this sound like, should i be worried.