Diagnosed a couple of months ago.
Just completed a two week 6000km ride in Australia.
I am lucky my attacks aren't as bad as yours and tend to happen at night or first thing in the morning. Second Sat on the trip I awoke and knew I was in trouble. Stayed in bed for an extra couple of hours and I then felt much better. You sound much worse then me.
Are you on medication? It's called Serc here in Australia. Meant to treat the problem in the inner ear. I have also found I need to reduce stress, reduce alcohol intake and get to bed early. Low sodium (of course, this is standard for Meniere's disease).
2005 KTM 640A