i am suspecious weather you are suffering from anxiety disorder which is called panic attacks. but before thinking the possiblity of anxiety disorder we have to make sure that you are not suffering from any physicall illness such as unstable angina, arrythmias and thyroid gland disorder. so first consult urgent care . they will do ecg , caidiac enzyme levels and tell you weather you have any acute illness. if they were not found anything get an appoinment from your physician. he will investigate further to exclude cardiac and thyroid disorders. if no abnormality found he may refer you to exclude posssible anxiety disorder such as panic attacks.