Chest pain in young women lasting for over a week?

I am a 22 year old female, in generally good health. I have had chest pain in the left side of my chest for over a week. The pain is somewhat localized to the left-center of my chest and occasionally moves to the center of my chest. It is not a stabbing pain, more like a sharp pain that is maybe a 5 on the pain scale. I have also had extreme fatigue and occasional dizziness and slight nausea. Also, I have also noticed that my extremities are weak, but especially my arms. I sometimes get short of breath after I have done something that normally is easy, ie. walking up the stairs. I went to the doctor and he said that it was probably a virus, I had an EKG and chest x-ray and they came out normal. He told me just to wait and see and if it hadn't gone away in a few days, then to come back. It doesn't seem like the pain is subsiding, so my main question is what can I expect as a possible diagnosis if/when I go back?