I have been having chest pain under my left breastbone for the past three days. The first day it wasn t that bad; there was just a heavy pressure but the next day a got worse and by night it felt like a sharp stabbing pain which carried out through the next day. It hurts to laugh. I can take deep breaths with only mild pain occurring but then I feel a little light headed. I checked my blood pressure and it was 110 systolic and 73 diastolic, I weight 129lb, i m 5 6, 18 years old, a women, and I have had issues with bulimia . I have never experienced this before and don t know how serious it is. Do you know what could be wrong and what could help?