Why does my BP go from high to low quickly and often each day?

There is such a thing as 'POTS'. Positional Orthostatic Tachycardia Syndrome. I'm not suggesting this is what you have. I'm only suggesting that you may need to find out IF you have this, or some other noteworthy, and potentially dangerous, cardiac response. Autonomic Dysfunction is another possibility. The way to do that is to be referred, or simply call/walk into, a cardiologist's office near you and explain your circumstances.
https://health.clevelandclinic.org/does-your-blood-pressure-fluctuate-widely-heres-why-you-need-to-pay-close-attention

Maybe it's the medications!

I take a beta blocker and that is what my cardiologist told me about the real high bp for less than a minute and then down the next is from the metroprolol.

I have SVT and it causes that.

It's normal depending on what you do for morning to evening for your body and your blood pressure to fluctuate that's normal. Our bodies and her blood pressure didn't fluctuate then if you look at Mayo clinic in blood pressure they said Amanda website of blood pressure is your blood pressure fluctuates throughout the day from when you're getting up when you're not stressed and then when you're going throughout your day from at your job site then it gets higher and then it goes down again when you're at home or calm than it goes back down again. Cuz being out of job or doing something can make your blood pressure go up and then when you go home again and come again it should go down again.

I just read side effects of beta blocker and one is low blood pressure, and also irregular heart beats.

I have SVT also. What medication are you taking for it?

That is what I have.....irregular heart beats and low blood pressure because I am also on blood pressure medications. I was told LONG COVID is causing the irregular beats. They are constant since two months after severe COVID end of last year. So 9 months of PACs and PVCs. The timing is right. But who knows.....:(. I get woozy but don't fall down like @thedad . My thoughts are with him.

I also had severe covid. Never went to hospital, and never took any vax. But my a fib was caused by caffeine, and not that much. After quitting, no a fib. You may be right, but I would suspect the FOUR meds. or beta blocker. Quit ALL caffeine if you haven't.

There are so many sites that claim to be associated with legitimate organizations, but aren't, so I'm wondering if this site is truly associated with the Mayo Clinic. If it is associated with Mayo Clinic, why are they allowing ordinary people to answer questions from other ordinary people about very serious health issues? We should NEVER be allowed to post our "diagnosis" or suggestions to anyone about their health. The only answer to any question posted here or any of these sites should be "Please contact a medical professional for diagnosis." This is irresponsible and could cost someone their life if they followed the advice of someone here. We all know how people will read something on the internet and accept it as gospel, especially if the answer helps alleviate their concern about their health issue. THESE FORUMS HAVE TO BE TAKEN DOWN IMMEDIATELY.