Shin pain

Hi- My wife broke her R tibia in 2013 and has had a problem ever since it healed.
It seems that after every time she runs her shin is sore.
The more she runs, the more sensitive it becomes.
She has gone to her Ortho Dr. 2x over the last 2yrs for x-rays, thinking it was broken, but everything shows up negative.
I am a runner and am not able to give any explanations for her pain. Any ideas? Could it not have healed right? Could she have compartment syndrome?
Shin splints? Any input would be great!Thanks,Greg McClung