chest pressure and tingling but results normal

I'm a 37 yo male. I am normal weight but do not exercise. My diet is generally low fat, less than 30 grams a day total. Probably closer to 20. I have normal blood pressure and cholesterol numbers in the low 160's. Last year at this time I had a scare. I had been out shoveling and though I was tired I felt fine afterwards. About 4 hours later I developed symptoms which I thought were heart attack. Chest pressure, not pain. aching in my left arm, tingling in my left hand and the shakes. I have history of heart issues. Well decided to call the EMT's. They did an EKG and some other stuff right in the house and said they could find no problems. They said they felt it was not a heart attack and more like something muscular but theyd take me to the hospital if I wanted. I decided not to go.

The next morning I was feeling fine for the most part but that evening the same symptoms flared up. Decided to go the hospital. After being there almost all night and them doing all the normal checks, Cardiac Enzyme, EKG's and chest xrays among other things they found nothing. A few days later I went for a nuclear stress test. Again, nothing was found at all. My doc felt it was all anxiety related, or possibly acid reflux.

Since then I been getting the chest pressure a bit on and off for the last year but never aching or tingling. Strangely it occurs moreso when I am lying down but I do get it sitting up to. I actually do take acid reducers time to time when the pressure flares up. Not sure it helps but I guess it does.

Well yesterday, almost a year later, I was shoveled again and within an hour it flared up the symptoms were more pronounced closer to what I had originally felt though not quite as bad. I don't know what make of this.

Why would this problem begin for the first time in my life right after shoveling and then continue on and off from then on. If it is acid reflux, why would shoveling have triggered the problem. If its muscular why would I have it a few times week all year even if I wasn't doing anything strenuous. I want to hear what others have to say because my doc feels its anxiety. I am supposed to see him soon for my yearly physical so I am going to discuss it with him again.

Thanks in advance,
Adam