There are all kinds of different possibilities. You should go to the GP unless it settles in a day or so.
My first bout was from an ear infection and lasted about 3 weeks.
Years later, it returned, far worse, and for no obvious reason. I was incapacitated. Months off work (got fired) months of no driving. I couldn't sit up in a chair without swaying in circles, I couldn't concentrate. It was fucking terrifying.
The consultant I finally saw said what had probably happened was that the first infection had damaged the nerves in my inner ear. My brain, being then younger, had automatically figured out that my ear was talking bollocks, and learned to ignore it, and compensate with visual cues. So the later bout was caused by a sudden failure of that compensation, probably due to a combination of age, stress, and other factors.
Physio was effective for me and I was back on the road and in work, but it took a long time.
There are other causes. Meniere's disease is one. There's a thing with loose buts of crap in your ear canals which is treated by manipulations that put the bits back in place.
The GP won't refer you straight to a specialist, but you need to start asking. If you have private healthcare, use it to get that referral.