Diziness , heart flutter. Fear already.

Hello, It's been 2 years I am having this issue I am I.t professional 27 years old. At the beginning I starts having dizziness and sweating all of sudden. I went through mri and all blood test only b12 was83 level. After few time I starts having detached feeling dr told me it's an anxiety. In that duration problem is still persists I starts having fluttering, dizziness, vomiting I do feel like pass out and going to be faint but I never. I had tmt, ecg done twice both normal. I am worried about arrhyt hmia but when this episode occur I checked my heart beat was normal no major fluctuations. I am not able to identify why I am having this issue. I did lots of test. Doctor says it's panic attacks but this episode are coming without stress situation . And last only seconds. No google answers please and no you tube I did lot of research need only professional answer I am in fear already.