Talk to General Physician on Fainting After Even A Small Injury

My sister, 21 years, Engineering student has fainted thrice after an injury. The first injury in January 2021 was a slight cut on the finger which followed slight bleeding. Her BP was low. Then she had an ankle twist in the university in March 2021 and fainted after coming home after about 2 hours of injury. The third time on 10th June she had a slight scratch on her foot, she was laughing but suddenly told us that she is about to faint. This time after fainting she had two jerks. Her BP was on the lower side when checked.She also had exams stress The fainting episodes last for less than a minute, few seconds to be precise. She complains at that time her ears are plugged, shortness of breath (the last time she fainted) and she has cold sweats only. Her blood reports are normal No shivering, no eye-rolling backwards etc. She never had any sort of surgery, no high fever can doctors help to diagnose? No fainting or jerking after that