I have horrible heartburn, and sometimes i have it as i swallow food down. it burns my chest, and i fear a heart problem. what could it be?

Unlikely: It is unlikely that a 20 year old woman would have heart disease and your symptoms are very atypical for heart disease but it does sound like you may have a significant esophageal issue. I recommend you establish with a health care provider who can do an EKG and get your GI tract evaluated and treated so you will not have these unpleasant symptoms any more.