Chest pain

I have a sharp pain that comes and goes below my shoulder and above my nipple. I have been to the ER 2 weeks ago and had a chest xray and a EKG. The ER found nothing and i am still haveing this sharp pain that comes and goes, Please Help!!!!
    Could anyone have a breif idea on what this may be? The chest X-ray came back neg. and the DR. stated that my potassium was low and my good cholestrol was low. Any ideas on what this can be?

[daisychic]

Im no expert, but just from my own experiences. If er did xray and ekg and all is ok with that. I have had severe chest pain before and it was found to be heartburn, acid reflux up in the esophagus, pulled muscle in that area. The reflux one was the worst. I thought it was a heart attack. It was so painful. After they gave me some stuff in er to numb esophagus it was much better. If you have a regular doc id just give them a call for a check up. Hope you feel better soon. Daisy