Posted 4/3/2017 4:49 AM (GMT -6)
Wait, you're on heart rhythm meds? I hope it is anxiety, and I certainly don't mean to make you more anxious, but if I was in your shoes I'd be getting that one checked out. But that said, after everything you have been through, it could be just anxiety. Some people are fine on that front until they have one or more precipitating events - and then, bam, they have an anxiety disorder.
Another possible cause of breathlessness, which I used to have, is severe anaemia. If I overexerted myself I could feel quite nauseous and giddy and have to sit down until it passed. It's worth ruling out anaemia as a possible cause.