High BP That Lowers On Deep Breathing, No Effectiveness With Food Or Supplements. Reason?

My blood pressure has been very erratic. By deep breathing and holding my breath, I can keep it down to 120/68 or less, but sometimes it jumps up to very high levels like 180/102. I bring it down usually immediately by deep breathing but some days it is very stubborn. Most of the time it is easy to control. I am normal weight, am mostly vegan but eat a small amount of goat cheese. I eat a really healthy diet and exercise daily. Am very active. I walk 10000 steps most days. A lot of it is aerobic. I don t take any medications . I feel they are just suppressive and I want to know WHY my blood pressure is high, not suppress it. I have had this blood pressure problem for about 2 years now. It used to be low. I am 67 years old and female. 5 ft 6 1/2 in tall and weigh 131. No food or supplement seems to help the blood pressure, just the deep breathing.