Hi should i go back to the doctor for palpitations its worring me. also what could cause this ?

And consider therapy: Yes, it's reasonable to feel as confident as you can that you are not missing a serious cardiac condition. But, after understanding the findings (if negative), please do consider the value of psychotherapy to learn about yourself and how your behavior and feelings can put such pressure on your body that it feels like a heart condition. You can learn ways to relieve or avois such stress and anxiety.