Male 83... BP flux 65/35 to 100/65 in a matter of minutes. .. pulse consistent between 60 and 65...blood oxygen level 95...medication for beta blocker?

Blood pressure. Low blood pressure can be life threatening. Causes include poor heart function, dehydration or too much medication, to name a few. You should be examined immediately and find out if those measurements are correct. Go to the ER or an urgent care now.