Correction: Hypokalemia combined with.. (the point was correct but mis-spelling)
You should NEVER trust advice about medications you get on forums. If you ask this question to a cardiologist on expert forum, he will probably answer that he won't give advice on meds, and neither should lay people like us.
I 100% second Ireneo and her opinion on letting doctors handle your meds.
It seems you have some kind of bradycardia (slow heartrate) and your BP is low. I don't think hypokalemia causes low BP and heartrate, anyway, hyperkalemia combined with low heartrate is possibly dangerous, and you should figure this out ASAP (if there is a reason to believe you are low on potassium). Most likely there isn't. Every electrolyte imbalance should be corrected as soon as you can, though.
You should never stop taking a heart medicine abruptly or without your doctor's knowledge and approval. It sounds like the medication is not agreeing with you and so have a talk with your doctor about alternatives. There are so many other heart meds available; no need to feel so miserable.
A simple blood test will let you know if your potassium levels are low. In the meantime you could try eating a banana a day and see if that helps. If your levels are way low, the doctor can take care of that as well.