Extra Heartbeats when sit up after a Deep Breath

Hello,

I was just lying down in my bed and felt as though I couldn’t take a deep breath. So I sat up, but as soon as I sat up I had 6 quick strong heart beats happen and it frightened the life out of me. I was then able to take a deep breath, but now I’m scared.

I have really severe health anxiety and have just had my heart checked out by 5 doctors and they said their analysis of my heart was absolutely fine, blood pressure was perfect etc etc.

What happened to me? I do experience missed and extra beats