Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.
Vertigo means a spinning sensation. Some people may define vertigo as sense of imbalance or lightheadedness.
Vertigo itself has several causes. These can be inner ear (most common) or from the brain itself. Inner ear causes of vertigo most commonly include benign positional vertigo (BPPV), which is due to small particle in the inner ear that moves out of place, and can be repositioned with simple head maneuvers. The symptoms often include vertigo that occurs with turning of the head, often while turning over in bed. Another cause, if your symptoms are associated with tinnitus (ear ringing) and hearing loss is called Meniere’s disease and can be treated with medications and sometimes surgery. And so on, several other causes from inner ear problems exist.
As mentioned, vertigo can also be due to problems in the brain. The most common is a benign tumor called a schwanoma (also called acoustic neuroma). This is diagnosed by MRI of the brain. Multiple sclerosis can cause vertigo, but often, other symptoms are present as well. A normal MRI of the brain excludes multiple sclerosis. Thyroid problems and basilar migraines can also lead to vertigo. Lastly, in rare instances of acute onset of vertigo, stroke must be in the differential.
If you mean lightheadedness, you should have your blood pressure and blood counts (e.g., hemoglobin) checked. Anemia and low blood pressure can cause lightheadedness.
Your history sounds most consistent with an inner ear source for the vertigo, which an MRI is usually not helpful. I recommend you following up with a neurologist or an ear, nose, throat specialist who can accurately diagnose your condition. As mentioned, if it is BPPV, it can be easily treated.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.