My Blood Pressure Has Been Controlled For About 10 Years

My blood pressure has been controlled for about 10 years with Diazide (triamterene) but as of yesterday it is running in the 168- 179 range (69-79 diastolic) Nothing new has happened and my diet has not changed. Yes I am 81 years old but very active and do work out at the local YMCA two to three times a week and live on three floors so
am on stairs a lot. I am somewhat overweight (about15lbs) but have been for many years. My blood pressure for years has been in the 130-140 range. I feel good but a little stressed now that it is up.
Please advise