Eek! If I were in your shoes, I stay on the current beta-blocker tonight and call the doctor tomorrow. That's just my opinion, not medical advice.

Please, read up on the med before you make the decision to take it tonight, especially if you are home alone. The little I read makes it sound unsafe to take under those circumstances, but I'm sure there's much more information out there than I've read.
Please check in with us tomorrow, so we know how you are doing.