What’s wrong with low blood pressure after activity and high blood pressure after rest?

  Patient: Description of the condition (time of onset, main symptoms, hospital visited, etc.): Blood pressure 120/70 after going out for exercise Blood pressure 167/84 after resting and drinking water at home I take Boydin 5 mg
What is the cause of this and what is the best medicine to use? Thank you!  Doctor: blood retention in the muscles after exercise, rest is equivalent to a large blood volume, each time to measure blood pressure to fully rest more than 20min, each time at least 3 times, every two times the difference is greater than 4mmhg to continue to rest re-measurement, the standard measurement of blood pressure is credible.