At many intervals of my adult life I've thought I was having a heart attack or heart condition with similar symptoms to yours. Been to the ER on several occasions for blood work, EKG, xray etc. All normal.
I've also dealt with heatlh anxiety for most of my life, convincing myself I had cancer in one form or other. After multiple ER visits, CT scans, MRI, X-ray and several specialists, I've always came back with a relative clean bill of health.