Occasionally having rapid heart beats, dizzy, short of breath

I am a little frustrated with being told I had abnormalities after doing various heart tests and having cardiac catheterization done but they stated they didn't find anything. Yet I still get these spells with my heart rate goes crazy, dizzy sweating and nausea. It doesn't last long but I am exhausted after it. These spells just come on sometimes after getting worked up or just casually walking my dog. It's a very scary feeling I dislike. Had mild heart attack in 2024. On half of metropol and that's it. I am thinking of second opinion I just don't feel safe and comfortable with this happening. Any suggestions or support that would be great. I am so lost in this I feel like they gave up on me.