I had a stress test and could not pass it due to shortness of breath, But they told me it was normal. Then they did a echo and it was normal. This was 3 yrs ago, when I walk, climb stairs, carry in groceries, the pain comes on in chest, into the right side of my neck and jaw, shoulder, and my heart skips. I had another EKG last week and I was told it was normal. I sit down when this happens and it goes away real fast. What could it be?