This sounds like muscle tightness and possibly a vertebrae out of place in your neck and or upper back.
Can you say what age you are? I'm asking because of your heart. We can have many different symptoms when we're having heart problems. If you're in your 20's or 30's then it's most likely what I mentioned above. I recommend you see your Dr to find out what's going on. If he/she thinks it's pulled, tight muscles or vertebrae out of place then a chiropractor might be able to help your pain.