Can that tiny little beta-blocker, hardly bigger than a pin's head really have made a difference? Already??

Probably. Some idiot GP prescribed beta blockers for me once when I complained of headaches. He diagnosed high blood pressure without either asking me about my history or coming within arm's length of me. I took 2 doses and ended up shivering in a heated room, wrapped in a duvet and wearing several extra layers of clothing. I stopped taking them (I spoke to my GP uncle) and everything was fine again by the next day and I changed GPs.