Vertigo is the feeling that you or your environment is moving when no movement occurs. Imprecisely called dizziness, the term vertigo is the specific term used to describe an illusion of movement. Unlike nonspecific lightheadedness or dizziness, vertigo has relatively few causes. ... Vertigo may...be caused by inflammation within the inner ear. This is known as labyrinthitis. This condition is characterized by the sudden onset of vertigo and may be associated with hearing loss. ... To determine if true vertigo exists, you must describe a sensation of disorientation or motion. ... The duration can be from minutes to hours and can be constant or episodic. The onset may be due to movement or change in position. ... The majority of cases of vertigo are harmless. And although vertigo can be extremely debilitating, it is easily treated with prescription medication. ... Specific types of vertigo may require additional treatment and referral: Bacterial infection of the middle ear requires antibiotics. ... The prognosis depends on the source of the vertigo. Vertigo caused by problems in the inner ear, while usually self-limited, in some cases can become completely incapacitating. The use of drugs and rehabilitation exercises are the mainstay of treatment. Most commonly this will make the symptoms completely go away or make the condition tolerable.The onset of my vertigo occurred either on the cruise or as we debarked in San Juan. I ran on a treadmill in the cruise ship's gym four times while we were passengers, but only the last time was while we were actually on the open sea. I remember struggling to keep my sense of equilibrium while the treadmill was rocking side-to-side with the ship (the irony is that that is how a treadmill on dry land has felt to me ever since we came back). It's common for cruise passengers to take some time to adjust to being back on shore, so initially I didn't think much of the fact that everything seemed to be moving. It appears now, however, that I picked up some kind of hardy bug during the cruise that has caused a long-lasting infection in my sinuses and/or inner ears. It's probably viral in nature, as a standard course of antibiotics didn't touch it. I have an appointment with an ear-nose-throat specialist in late-April (having consulted already with our primary-care doctor), but that's little comfort. I'm certain there are plenty of people with terminal illnesses who don't feel any worse than I do at this juncture!
[Update 4/1/10: What I have now seems more likely to be "mal de debarquement". It's reportedly rare for a man to get it, but everything fits, right down to the fact (a) that it isn't caused by an infection of the sinuses or the inner ear (which I really don't think I have), and (b) that neither Meclizine nor Scopolamine has any effect on it, whereas Temazepam (one of the sleep meds I use, and a benzodiazepine) seems to help somewhat. It's really dismaying to know that the symptoms of MDD can last for years, however -- I don't think I can live like this indefinitely!]