Concussion symptoms can last years. But that does not mean this is a concussion symptom. The very short duration is odd unless these moments follow a movement. I have had a momentary problem like this since 1987 when I had general anesthesia for a broken Tib-Fib. I had to learn to not start to move in two dimensions at the same time. Getting out of a chair, I need to move forward before starting to stand up, otherwise, there is just too much movement.

What has been done to help you diagnose this problem ?