What Causes Severe Fatigue While Suffering From Hypertension?

My wife has had a complete heart workup with imaging stress test, etc. and no blockages, in fact she did way better than average and moved 10.5 times the oxygen that she would have at rest. She has low bad choleserol and is 120 lbs at 5 7 height. She can tolerate vigorous exercise very well. She has been experiencing blood pressure that has been bouncing around and ranges from 136/89 more typically, up to circa 167/110. There does not seem to be any rhyme or reason as to when or why it is elevated. She sometimes feels quite weak and tired, usually in the morning. Her normal state is high ambition and like the Eveready bunny, so it is very unusual for her to feel this way. It has been going on for 6 weeks or so and she has days when she feels normal and days when she cannot understand why she feels so lethargic. We re not sure what else to explore to figure out what might be wrong. What are your thoughts?