The commonest cause of pain in the rib cage
area is due to muscular spasm.
Mild discomfort in breathing is in favour of muscular spasm.
in this situation I would advise my patient to relax.
Give yourself adequate rest.
Inspite of the above measures if the pain is not subsiding then you need to consult your doctor.
He may advise you an ECG and X ray
of the chest to rule out any other cause that may be creating the pain.