What could cause blood pressure fluctuations in a 49-year-old?

Hello doctor,

I am concerned about my mother. She is 49 years old, height 5'4 feet, and weighs 75 kg since she refuses to go to a hospital. She is been diagnosed with hypertension since her 20s. Her average BP is around systolic 130 to 140 mm/Hg and diastolic 80 to 90 mm/Hg. But there was a time when her blood pressure shot to 180/95 mm/Hg. She was already checked with the doctor with all the laboratory tests that came back negative for any complications. Her blood pressure is sitting around 110 to 120 mm/Hg systolic and 80 to 90 mm/Hg diastolic since then. She keeps skipping her medications for one to two days. She got diarrhea and her blood pressure reading went up to 190/120 mm/Hg. The problem is, she refuses to go to see a doctor and just took her regular medication which drastically lower her blood pressure in a few hours. Do we still have to see a doctor and have her checked? Kindly help.