I am using an omron machine at home to measure my bp. I take 3 back to back readings in sitting posture and calm environment. However almost everytime there is fluctuation in my reading. The fluctuation typically is by 10 to 15 readings in systolic and 8 to 10 reading in diastolic. Is this considered normal? My last month bp varied from 122/77 to 142/91 with an average of 131/85 in 13 readings. Is this normal? Please advise.