X- Ray findings suggest that everything is normal. The sporadic chest pain
may be due to excessive coughing, or bad posture or carrying a heavy bag or any other incidence of trauma. If she does not have any other complaints like cough or pain in the legs, weakness etc. then there is not much to worry about. Also you must ascertain, can the pain localized to a single point, or is it generalized. Is it at the same place every time? If she continues to get such kind of pain and you cannot pin point a cause then you may consider checking her Calcoum & Vitamin D levels. Or else nothing much to worry about.