Why does my blood pressure go from really high to really low within min all day everyday?

Fluctuations: Blood pressure does fluctuate, but shouldn't fluctuate greatly if the activity level is the same. More likely is the accuracy of the measuring device. Bring this in to your next doctor's appointment to check its accuracy.

Labile BP -> See MD: Blood pressure is an every changing number and can be affected by position, hydration, stress, foods and other mundane things. However, if you notice your blood pressure numbers swinging wildly (> 35 point jump at rest in either the top or bottom number), this could be from an endocrinologic problem. Certain hormones may be overproduced resulting in sudden high BP readings. See your doctor.

BP: A normal and healthy response to exercise is for BP to rise. If you measure your BP at random times during the day without resting 15 minutes, you'll see wide fluctuations. You should always rest before checking your bp. Measure it 3 times in a row. If it drops significantly on the subsequent measurements, you've conditioned your self to become apprehensive with the measurement.