Go to ER....
Shortness of breath can be due to many, many things but it can be a life-threatening symptom. A bruise on the patient's chest could be due to trauma of some type and, combined with shortness of breath, necessitates a trip to the er to be certain there is not a serious, life-threatening process going on.
There are other etiologies for the bruise but please go to the er today! good luck!