It sounds like a persistent version of dry land sea legs. There are a few names for it. It is common when somebody has been on a boat or ship that moves and the brain/vestibular system has developed an accommodation for the movement. Then, when you get on dry land, you feel like the land is moving.

I experienced it once for maybe 5 or 6 hours after spending about 40 hours on a sailboat. It was a strange sensation.