You need an MRI or a CT scan of the head. A space occupying lesion in brain or loss of blood supply or aneurysm can be the possibilities.
Following are the other common causes in your age group;
1) Acoustic neuroma
2) Vestibular neuronitis
3) Inner ear diseases; mainly these are autoimmune disorders and may have other issues associated like arthritis.
4) Benign Paroxysmal positional vertigo.
6) Meniere disease.
Following are the investigations which will clinch the diagnosis;
2) vestibular tests.
The most commonly performed vestibular tests are as follows:
Electronystagmography (ENG)The rotating-chair test, also referred to as sinusoidal harmonic acceleration (SHA), Computerized dynamic posturography (CDP).
3) blood tests for autoimmune disorders,
4) computed tomography (CT), and magnetic resonance imaging (MRI).
Please feel free for your follow up questions.
I would be happy to assist you further, if you need any more information.
Thanks for using Just Answer.