Same here on the big and tall spaces, though not in a building...just driving over big mountains(never had that before) or looking out over an overlook that is high up...never had that before either. Just like you, it's been in about the past 5 years as well. Call me crazy, but the Earth is moving more nowadays and I feel those with a more sensitive inner ear seem to be feeling it more than others. I'm thinking we feel it all the more in these types of situations.
Another thing that has been happening in the past 5 years at random times...and this has nothing to do with fluid on the inner ear and such, nor motion causing the otoliths to move. I can be sitting still with my head completely still and the room does that same thing you describe. Feels like I'm on a ship and the deck is tilting.
I've been walking along before and just start staggering to one side and the earth seems to be tilting, causing me to feel dizzy. As a nurse, I was thinking I was having a health problem...until my mother and one of my sisters reported having the same kind of episodes and in the same manner and all starting during the same time frame. That earth is movin', folks!