Heart Beats Super Fast Until I Lay Down

[mrstlee]

So I've had this for as long as I can remember, and I'm currently 28. Not overweight, and I don't take any medications or have any health issues - not even high blood pressure or cholesterol levels. However every now and then, maybe every few months or so, my heart starts pounding really fast and I get super light headed. If I lay completely flat for a few seconds though, then it feels like my heart stops for a beat and starts back up again beating completely normally. The most common cause I've noticed is bending over and getting back up quickly but sometimes it also occurs outside of this trigger. I've been googling and googling and can't find anything like this. Anyone have something similar or know what it might be?

[Gemfly]

Get your ferritin, vitamin D checked.

Make sure you get enough magnesium and potassium so your electrolytes are in balance