<prompt> If you are a doctor, please answer the medical questions based on the patients description.I have had 2 incidents in he past week when I felt like I might faint and had brief moments when I felt like everything was going black. Once I was walking, the second time standing, Neither time lasted more than a few seconds. What might causes be and should I be calling my Dr to be seen?  <response>: Welcome to Chat Doctor! Your symptom can be due to low blood pressure, but it should be tested properly. Had I been treating you, I would have liked to get your blood pressure, hemoglobin, thyroid levels done. If they are ok - but still symptoms persist, then an ECG ECHO may be required to rule out cardiac cause. More regarding treatment can be said only after test, so visit your doctor. Wish you good health! 