To ed34: Thank you for your reply
I think that rather than wonder if you were having a heart attack, you should have gone to the hospital to be sure. Most people lost valuable heart muscle because they just wait to see if the pain goes away. With regards to your question, it would be easy for everyone on here to give a possible cause for your symptoms, but that's just is, they are 'possible'. What you need to know is what the real cause is and this takes tests. A troponin blood test will show if your heart has been under attack and because it has been happening for over 12 hours, they can do this immediately. You also need an ECG. I really wouldn't wait, I would get to your Doctor or the hospital now because time is muscle. It is highly probable that it is nothing to do with your heart, but how will you ever know. Please go and be checked out now.