I have been diagnosed with chronic migraines. No headaches and very similar symptoms, I also pass out and have had seizures. I have been given gabapetine and pizotefen, I have medication for other issues too.
My neuro just put me on atriptyline (very similar med) for migraines. I lasted 2 whole days. You're a trooper for lasting longer. I had the brain fog and drowsiness until late afternoon the following day, and it took 3 days to get past that.
I don't get vestibular migraines, but a good friend does. She is on topiramate, and has had some decent relief from it.
I take topiramate, trazadone for sleep, and a beta blocker. I also have heart issues, so the beta blocker does double duty, as beta blockers can help migraines.
Vestibular migraines are thought to originate in the ear, so you might need to add something like ativan, an antihistamine, phergan, etc., for dizziness.
I wish I could tell you that your journey will be easy, and that find a treatment that works will be smooth. It probably won't. Migraine treatment is tricky, and what works well for me might not work for you, and you'll probably try several meds before landing on the med or med combo that works best for you.
Hang in there and hugs to you!