I am a member of a GME group and I asked one of their techs about Raindrop.... basically I was told that Vestibular Syndrome can be a symptom or caused by GME.
The reason I am being a pest about this
is that GME is fatal unless treated, and the sooner it is treated the better the outcome for a total and complete recovery. Most general Vets are not used to looking for or diagnosing GME and may not even think about it unless you mention it to them. You will have a better shot with a neurologist, as they are more current on GME/NME/Chiari (as it's more their field).
As Raindrop is so young to be getting VS just for any reason, I really implore you to have a neurologist investigate the cause of her VS asap, as she responded once to steroids (which are also used to treat GME), and doesn't appear to be responding too well to just the VS meds.