Male 29, palp update, panic attack possibility, medicine reaction possible

About a month and a half ago I began having heart palpitations. A few weeks later, I had an extreme episode (BP 140/110, pulse 150s) that made me panic so I went to doctor next day. I had both a normal EKG & chest x Ray and got put on a holter monitor. A few days later I had another episode (pulse got up to upper 130s, BP shot up but both came down within 30 mins) and went back. I was prescribed metoprolol tartrate (25 mgs two times a day) and have felt better, but Friday I had an episode where I felt like I was having trouble swallowing and some tingling in my fingers. Pulse only got to I think 117, but scared me again and now waiting on holter results. Doc said it could be PVC or another type of contraction, but we have to wait on results to come back. Any thoughts on this or seriousness of it? I'm pretty scared of Afib or another condition and want some assurance about what the possibilities are. I've not passed out and jot had any pain besides some slight little pains. Any advice?