Sounds a lot like what I have going on. My doctor says they are harmless; probably heart palpitations or PVC or PAC (where your heart kind of skips a beat). I know they don't FEEL harmless, I had them for years without really getting worried, then I had one VERY strong one that terrified me enough to go to the doctor. It felt like my heart did a flip in my chest and then my pulse felt eratic.
So, he said it can have to do with all of the following:
- being a woman (hormone fluctuations)
- stress and anxiety
Geez, basically anything!! If they really scare you, head to your doctor. If its anything like mine, he will rule out anything serious and tell you not to worry. Easier said than done!