Gardengal, have you tried 2.5 gm/day? I corresponded a bit with the very much appreciated Dr. Gacek. He suggested I try 2.5 gm per day. I did that for many months, but just recently had a setback and went back to 3 gms/day.
Interesting about the posts of not being able to drop down on valcyclovir, I started acylovir on July 22, 2015 and have not been able to cut back yet, I want to go at least one whole month without any vertigo before I cut back, and maybe I won't cut back right away, maybe I should go two whole months without vertigo before I make any changes. I've eliminated coffee from my diet for MAV, I have had a couple of days of no wobbliness, but whenever I have a little dizziness I take meclazine because I am afraid it will turn into full blown vertigo. We've had some weather changes and my tinnitus went back up yesterday, I used to hate the tinnitus, but after vertigo started I decided tinnitus is easier to live with (except it makes it hard to hear) than vertigo!
I noticed some vertigo when initially going from the 3000mg to 2000mg so my doctor kept me on the 3000mg for an extra 2 weeks. After that I had no further issues. I would keep with the high dose for a couple more weeks if your NP is okay with that.
It has been a year now since I started with Valaciklovir. I have not had many bad Vertigo spells since then. I can only think of one now, last autumn. Now when autumn is coming again, I feel worse. Today I am increasing to 3000 mg as I have been on 1000 or zero for many months now.