Suggest Treatment For Exercise-induced SVT And Elevated Heart Rate

I m a 57, very active woman. I had exercise-induced SVT treated by ablation in 2013. Two days ago, my heart rate went up to 125 while sitting. I went to the ER where everything was normal...except the treadmill; went back into SVT. I was prescribed diltiazem 2x a day. I still don t feel right. My heart rate is still a little elevated, I m not hungry, and feel fuzzy headed. Is it the diltiazem making me feel this way? It s 30mg and I took it at 5:00 am. I m seeing the cardiologist tomorrow.