It could be sinuses. You can go without feeling any symtoms of sinus problems at all. When I began feeling off balance I didn't really feel many symptoms. Just a bit of congestion. I surly did not feel anything wrong with my ears either. Most of the time people don't. It could fluid in your middle ear, could be mucus built up in your sinuses throwing off your equilibrium.
As for inner ear infection, there's no pain or anything. It doesn't really sound like that but it could be. It's hard to tell.
Have you been having any stress in your life? Could be anxiety. It's hard to tell. But to me does sound more like your ears and disequilibrium.