Hang on in there PL, I hope they find out what the cause is, or conclude that it's nothing.
I'm in a similar situation at the moment, I had a routine ECG some weeks ago as part of something else, get a very panicked call from my dr on Friday morning saying "come see me today, don't panic" so I started freaking out and had to race to London from Liverpool.
Was sent to the cardiologist first thing Monday morning for a barrage of exhausting tests after a very worrying weekend and yeah, there's something up with my heart.
Had to wear a very uncomfortable heart monitor for 24 hours and I'm now waiting around for an appointment to have my heart MRI and to see what my heart did over 24 hours.
The thing is, I can feel the heart beats, and I know they're weird, I get like double beats then it misses a beat then really thunders in my chest, lying in certain positions exasberates it etc.
I'm pretty scared right now, I know that it's probably, hopefully nothing, but I'm concerned, I didn't expect heart problems at 25.
I've come to work today but they're sending me home at the end of the day, (we normally finish around 11pm) to have a few days off whilst I wait for results.
I hate being off work as I love my job and we're at a critical point in our development.