Chest pain sometimes. Please advise!

From last 5 months, I have been facing chest pain sometimes and also shortness of breath frequently. Generally, i have axiety problem due to which I generally face shortness of breath especiallywhile doing scuba diving, parasailing or during public speaking (as I realized it). Last month, I had fish fry one night and after 30mintes I felt restless and felt like I will faint in few minutes. I was rushed to hospital immediately, they checked ecg and other tests however doctor said everything was normal. I have visited gastroligist recently and explained my problem. He suggested me to undergo endology and ultra sound of  abdomen as was also burping frequently and said that if both the reports are normal then we need to do cardiac check. Apparently, both the reports are normal. 4 months ago, I have also undergone body check up as part of regular activity. All the reports were normal except B12 deficiency. Also during treadmill test in final stage, the heartbeat was abnormal. please advise