I Am Feeling Woozy And Disoriented With Head Movement. I

I am feeling woozy and disoriented with head movement. I can look up at a student and then down at a paper and feel woozy. Sometimes I don't notice that head movement is involved, but it usually is. There has been a few times where the room was spinning and I have needed to hold on to something. This has been occurring off and on for a few weeks. Seems to be getting worse. Even now, looking from the keyboard to the screen is slightly disorienting. Wondering what this could be. I have a cruise coming up and am worried about increased symptoms on the boat.