I had a period like this in college. Never did figure out what brought it on or what caused it. I remember laying in my bed in my apartment and feeling like it was going to toss me out the window it was spinning so much. It was horrendous. The meds the health center gave me knocked me flat out too, even taking half doses.
Try looking up Meniere’s Disease. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001721/
Eagle Syndrome (a long shot but I was recently dx with this after years of symptoms). http://en.wikipedia.org/wiki/Eagle_syndrome
Let us know if anything improves.