Way back when, I had severe bouts of vertigo. Felt like I was in a boat on the ocean rocking to and fro. Went to neurologists, specialists etc. 15 years late it was found I have Hashimoto's disease.
When you say your levels are normal, that is something that I had to struggle with for those 15 years. What is normal is not always normal for other people! Those 'numbers' on the lab tests are just an average and then you are told you are normal. Since you are having fatigue, nausea, etc, you are probably not 'normal' for you.
Another factor in vertigo is low iron. I had that too! Have you been tested for low iron?
You do need to get full thyroid function tests and let us have a look to see what is going on.
Meniere's disease was suggested to me. Which is a middle ear glitch which can lead to vertigo. I didn't have it. Has your ear specialist mentioned this?
You might need to get some adrenal gland tests done as well. If your sodium and potassium are out, depending on which level they are, you could have adrenal fatigue.
Can you post the thyroid labs and the results? Also have you had an A1C blood lab done?