Possible cause of sporadic Ectopic(?) Beats and occasional irregular pulse?

[Atum87]

Around 5 or 6 years ago I had a year of popping in and out of the doctors initially because of a strange and continuous fluttering in my throat that seemed to come on randomly, last a few hours (sometimes whole days) and then return to normal. The fluttering would arrive every 10-15 seconds or so, last for just a moment which and then was followed by a rush from inside my chest cavity ending with very brief rush to my head/eyes which was akin to a momentary shock sensation.

Finding that this sensation was linked to my heart rate was what led me to see a doctor, but every time I went in I could only explain my sensations as they had long passed by the time I had an appointment booked.

I was finally able to see a doctor when the feeling was so prominent and frequent that it kept me awake one night and I drove to A&E fearing the worse. The doctor witnessed my heart rate on a cardio graph which they kept me on for 2 hours (at least) and explained that they were ectopic beats which I could 'reset' my heart beat with a splash of cold water to the face. He also asked me about caffeine and cocaine neither feature in my diet apart from the occasional coffee which is at most twice a week.

He also explained that this feeling was an extra and larger beat of my heart thrown in between it's normal rhythm (which explained the rush I felt too) and that the extra beat was enough to make the normal heart rate feel like I was missing a beat at the times it wasn't there and that the anxiety of noticing that gap had only perpetuated that inclusion of more ectopic beats.
I was booked in for an echo scan as a precautionary measure and during the scan everything was found to be fine.

A couple of minor episodes have happened since (perhaps 3 a year now) but they are gone as quickly as they have arrived. My concern today is that, every now and then, I will receive one larger than before beat (or that's what I've assumed it is) randomly at points where I don't expect it, and today was the largest one I've felt to the point it cut me off mid scentance and I needed to compose myself briefly before continuing. I also remembered that, last week, after some general assertiveness of moving some furniture upstairs, my then elevated heart rate seemed irregular again but did not seem to have the inclusion of ectopic beats but just be completely random - I wouldn't have noticed this if it wasn't pounding hard to the point I could feel it in my ear drums.

After that bit of background (and probably a hundred iPhone autocorrect errors!) my question is;
Do I just live with these ectopic beats and are they going to progress to something more serious as I get older?
Could there be a link to the smell of raw linseed oil or oil paints - I am an occasional painter (canvas, not walls) and I remember now that the last time I had a problem like this my house stunk of linseed oil.

About me: I am male, 29 (problems started around 22-23), I consider myself fit in that I play football casually once a week and use the gym for weights, I drink occasionally, don't touch drugs, have a poorer diet than I'd like to admit (I have a bit of a sweet tooth) and I do office work for a living.

I'm really just trying to find a cause or calm my worry that occasionally comes in when I feel this so any help would be greatly appreciated - thanks for reading!