High blood pressure and Byst do olic

My name is Gianluca and I'm35 y old m. Recently I've been experiencing blurry vision, flashing lights in my eyes, and dizziness when I stand up from sitting for the past 3 weeks so I went to my PCP. He measured my blood pressure and it was 148 over 105.
He prescribed me Bystolic, 5mg for 5days.I work out up to 6 times per week, and am a non smoker/drinker. I am a little concerned about this medication because I know that when you start beta blockers it is hard to stop.
Also,I did take 2 stress tests in Italy - one 2 years ago and while I was running my blood pressure was a little higher than usual, and one 6 months ago and my blood pressure was normal. I did these because of my headaches. If this high blood pressure is just due to periodic stress, isn't the prescription of bystolic a little premature? Can I stop taking the medication without side effects after the 5 days? I bought a blood pressure monitor today, on my first day of taking the bystolic pill, after this morning's visit to PCP, and my blood pressure tonight, 6 hours later than the pill, was 109 over 62. Isn't there a risk that my blood pressure goes too low? Am I safe if I take these pills for 5 days? What could happen if I stop taking the pill after the first day? I don't know, I feel like the pill was prescribed a little prematurely, because I think an episode of high blood pressure can happen. I trust my PCP, I think he is great, but maybe I just need more of an explanation. I am really worried that once I take this pill, I cannot stop taking it even if might not need it and I don't comletely understand why he told me to not run or to do any physical activity.What should I do? Just take the medication and wait for the follow up? In which case should I stop taking it during these 5 days? The first day so far was ok and actually my headache is really mild now, but I am still concerned about the side effects and if I really need this.
I thank for your time. G