Why does the left part of my chest hurtso bad?

Many causes: You must first rule out cardiac cause of chest pain. You should go to a cardiologist, have him test for cardiac isoenzymes, have a echocardiogram and possibly a thallium stress test. If cardiac cause is ruled out, then you have to consider lung or gastroinstestinal problems , other masses in the chest, and lastly muscular strain or sprains, spasms, or connective tissue inflammatory disorders.