Beta blockers lower blood pressure so if your pressure is already low, I would definitely see a cardiologist for alternative meds (calcium channel blockers were offered to me). I believe it is good to taper off the beta blocker you are on but maybe not if only one week: ask your doc or a pharmacist.

It might help to do a longer heart monitoring. Have you done that? Have you had an echocardiogram?

The cardiologist might even be reassuring. Hope so! I know tachycardia is uncomfortable. How high does your heart rate go?