Swimming feeling can be a result of extreme panic and anxiety too. I have a general feeling of unsteadiness like im rocking swaying and tilting. No cause and ive seen tons of people having it from GAD, which i have. It tends to go away in time. Its like dr dp, if you constantly fixiate on it it will persist. Your balance isnt just controlled by your ears. Your eyes and senses have a hell of a lot to do with it too. So it can be because of your visual disturbances too.