It sounds very similar to mine. I was diagnosed in 2019 with vestibular migraines, even though there's no headache type migraine involved. Like you, I can go to bed feeling fine, then I'm woken up in the early hours with the spinning sensation, vomiting, no balance etc. It's brutal and I wouldn't wish it on anyone. Once it kicks in and after the vomiting and loss of balance has eased slightly, (usually after about two hours), I can usually sleep it off in 4-5 hours, if I lay perfectly still. The Epley Manoeuvre helps with everyday BPPV, but it didn't make any difference for me, for these severe attacks. The only treatment offered to me was for beta blockers, which I can't take unfortunately. Good luck with the doctor and hope they can help.