I don't know if you still have this problem, and I don't know much about AN's, just got diagnosed and haven't even seen my doctor yet as the results of my MRI came while she's on vacation. BUT I do know about vertigo.
I have had debilitating vertigo like yours on and off for years. I heard recently that there are some specialists who are better than others at treating it with "exercises". I sought one out and ended up with a physical therapist who specializes in this. She tested me, thought it was a very clear case of BPPV (benign paroxysmal positional vertigo) and miraculously cured it in a short time, not really using exercises, but by slowly positioning my head while monitoring my eyeballs. With this kind of vertigo you see the room spinning because your eyes are actually moving. Also reading your story, I noticed that it sometimes starts for you when you're lying in bed, which is very common for BPPV.
It was my inability to completely improve with my balance and dizziness issues afterward that led to my doctor ordering an MRI and finding the AN. From experiencing both of these I think that the dizziness from the BPPV and the AN are different and feel different to me. Apparently I had them both at the same time. The BPPV was in the right ear and my AN is on the left. But I may not actually know what I'm talking about since I have not seen my doctor to find out about my AN yet, and I'm a newbie here, so take this with a grain of salt.
Still, if you are having this problem you might consider looking into a vestibular therapy for those with BPPV in addition to whatever you have to do for your AN.