Whenever I think i've had it bad, someone comes along to prove to me, I've had it relatively easy. So sorry you got this so young. Have you ever been explored for congenital fistulae?
The problem with Gentamicin treatment is that, apparently it leaves most patients with chronic imbalance. Also if you are bi-lateral there is even more risk, I understand. It makes more sense in someone who has lost all hearing I would suggest.
Perhaps its because my hearing is unaffected during vertigo, perhaps its because my vertigo is almost always relatively mild and relatively short in duration, but I would certainly say that chronic imbalance and nausea is FAR worse than my vertigo spells. And let's not get on to de-realisation, head fog and head pressure ...
I think there is a botox treatment for VM, but can't see how it addresses the root cause. I'm not aware of any other injection therapy for VM.
In the UK Gentamicin injections are no longer recommended, watch the link:
It's my opinion that VM is actually Secondary Hydrops, which is more common than Menieres but clearly shares some mechanisms, and symptoms. However, hearing loss is very mild in VM and patients don't get a profound decline in hearing. Take a look at this thread:
All the best of luck!