H.W.
This happened to me after being out at sea on our ship (Navy) for a week doing circles in the water. Your sense of equilibrium learned to compensate for the movement while you were out on the water, now it will take a little bit to return to normal. I promise it will! Took me a day or so, if I remember correctly.
I think that if it's been three days, you might want to talk to your doctor, just to rule out any other possible factors.