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.
Dizziness can mean multiple things. Some describe dizziness as spinning sensation, others lightheadedness or imbalance. The most common cause of dizziness is benign paroxysmal positional vertigo (BPPV). However, you describe more lightheadedness feeling, rather than a spinning sensation. (BPPV is classically a spinning sensation that is worse with turning head or rolling over in bed).
Dizziness can 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, such as numbness, weakness, vision changes, etc. A normal MRI of the brain excludes multiple sclerosis. Thyroid problems can also lead to dizziness.
Your symptoms may be consistent with a variant of migraine called basilar migraine. Basically this is marked by several hours of dizziness associated with nausea, light-sensitivity, and sometimes other symptoms. Headache may or may not be present. The treatment is different from that used to treat other migraine types; the treatment in this case is a type of medication called calcium channel blocker, such as verapamil, which is actually used to treat blood pressure but works in type of basilar migraine as well.
Lastly, low blood pressure, such as from, dehydration or autonomic dysfunction, cardiac problems, and several other non-neurologic causes can cause lightheadedness. Anemia can cause light-headedness as well.
I would suggest you follow up with your primary physician. If a source cannot be found after thorough blood workup (which would include a thyroid panel and glucose testing), an MRI of the brain with and without contrast may be necessary.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.
Thank you so much for getting back to me!!!! It helped a lot. Right now I'm in the process of getting an mri, but everything else was ruled out. I also went to see an ENT today and he didn't seem to find anything either.