In case it helps anyone...

Woke a month ago 3am with a cold sweat feeling awful following day 3 of a cold treated with pseudoephidrine. changed position and felt breathing was difficult. Lay down as flat as possible and heart gave a weak pulse, seemed to stop for a couple of seconds before THUDDING back into a racing rythm. Got an ambulance who saw some arythmia on the way to hospital. Tingling hands on and off but recovered with breathing exercises to control any hyperventilation. Discharged in hours but palpitations at home, especially on resting (the longest run was next night for 6 hours). Seen a couple of times but ecg fine, echocardiogram and holter show no major anomolies. Palpitations frequently accompanied by excessive belching / burping, getting worse over a month. Never any pain or indication of reflux.
Another cold with constant burping for 12hours straight, accompanying palpitation runs with  heavy and missed beats to boot, making sleep almost impossible. Got a script for Nizatidine, Nexium and benzodiazepam. Took the proton pump inhibitors first as i was worried about bradychardia on valium and symptoms lessened onough for sleep within 3 hours. Never took the valium and by next day 95% improvement in symptoms, palps and burping. Fingers crossed it holds out!

The best guess on the initial problem from my doctor was myocarditis, possibly with anxiety driven follow-ups. The recent response leads me to think the gastro-intestinal problems may have been driving a bunch of symptoms- althouhh breathing exercises often helped rein in the palps.

Good health and good luck to all.  

Query myocarditis. A definitive diagnosis would require biopsy, given it was minor no biopsy was going to be had unless worse symptoms presented. A cmri might help with diagnosis but given ejection fraction was good the value wasn't there. Additional trips with palpitations but no brady suspected as anxiety given age and ecg made a chronic problem only 2% likely.

Myocarditis that only shows up on cmri has been shown to occur, although by all accounts if that's what I had it's very mild indeed.

I don't know if a nuclear test is warranted, I'm only 32 and seem to be improving with time.