Bottom number in blood pressure is high, what to do?

Go see your doctor: Actually, first re-measure it (which I'm sure you've already done). Then take a deep breath, wait 5 minutes (don't hold your breath! just breathe normally) & recheck. Also check your equipment. Did you drop/damage your BP cuff? Run out of meds? Start smoking (more)? Drinking (more)? Stop exercising? Eat more salt or salty foods? Sleep less than usual? Be sure to bring BP cuff in for calibration