I am 46 year old female, have been having shortness of breath, difficulty breathing and my left elbow was hurting a little bit. Went to hospital, blood work, chest x-ray and ekg were done, nothing showed up but an elevated d-dimer (1.0). The doctor ordered a cat scan with dye to rule out a clot/tumor, showed nothing. I have not been feeling well at all. What could this be?