My Sister Was Walking And Her Head Was Tingly, Saw

My sister was walking and her head was tingly, saw stars, tingly arms and legs, shortness of breath, weak, for about an hour. She does have a history of high blood pressure but when she got home from walk her blood pressure was low 85/54.
Do you have any idea as to what might have happened?
Another thing -- three weeks ago she had a Transient Global Amnesia episode after working out.