What Causes Right Chest And Back Pain While X-ray Report Are Normal?

For 48 hours now I have been experiencing right sided upper chest pain, it has gradually gotten worse including shortness of breath, feeling nauseous, and now pain radiating into right shoulder and back. Last night I went to the emergency room and they performed an EKG, blood work and chest xray and nothing was found, still 24 hours later I feel worse and now experiencing more pain in my chest and now in my back. Should I go back to the emergency room?? I took tums as well and nothing has changed.