Is Low B12 And Irregular Heartbeat Linked To Shortness Of Breath And Lightheadedness In A Healthy Adult?

Hie I m 28years old l went for check up because l was experiencing shortness of breath, weak hands and feet and also light head. I went to the doctor and they found out that l have low vitamin B12 and also heart beat irregular. Now I m feeling that my heart beat is at it again and in having light head. Please help