Lately, I've been experiencing a weird sensation, while sitting and standing, of unsteadiness. However, it feels like the unsteadiness is not internal but external, like during a very mild earthquake. The feelings worsens when I move my arms (writing, stirring while cooking, and so on).
The feeling is alarming and frightening. If anyone has any clue what could cause such a symptom, or has an advice, I would appreciate the input.