I believe the eustachian tube in the ears is connected with the sinuses. When you have problems with sinus, it can impact that tube and at times it can cause vertigo.
Also when I had some vomiting, it set off vertigo for two weeks and the doctor said that can happen after vomiting and if it didn't stop he would do a procedure--it did stop after two weeks so I didn't have to have the procedure.
I also started with Nyagstamus (spelling?) of the eyes (feels like they are rolling back) and vertigo during two weeks of migraines. I saw the neurologist that sees me for migraines and he said that is a symptom that can occur with migraines sometimes. He checked me while I did not have a migraine and there were no symptoms so he knew it was not a neurological problem, but related to the migraines. He did the occipital neural block (needles) and as usual that stopped the migraines for a while.
Here is a safe site on the Eustachian tube and some disorders it can have.
http://emedicine.medscape.com/article/858909-overview