Hi there Loll and all
I too have these and have had them for about 30 years, I was very anxious about them when I first got them, but when I was told what they are I lost my fear of them (Good job 'cause I have so many other symptoms that freak me out, lol). They are called extrasystoles and anyone can get them even healthy people, of all ages. I usually get up and walk around and burp (lol), I think that it might have something to do with wind around the heart like indigestion, please take it from me they are not harmful, if they were I wouldn;t be here now after all this time, but I know they are upsetting especially when you get them one after the other, it feels worse than it is. I hope this helps you.
Take care
Elspeth