I’ve had similar experiences in the last few years (mid-40s).
Before I started HRT at 43 I would get pre-menstrual dizziness - the GP currently thinks this is vestibular migraine. I don’t get it so often now, only very occasionally. However I have found the Epley manoeuvre helps so I think that at least sometimes it’s BPPV and not VM.
About a year ago I was getting bad vertigo. I remember sitting up in the Starbucks in the Bullring in Birmingham and the view down into the shopping centre gave me that motion sickness feeling (I do get motion sickness anyway). GP started me on utrogestan after that and I’ve felt much better since.
But like @FlossySamI’ve also had short intense nausea too. It was particularly bad mid morning a couple of summers ago (I was doing intermittent fasting at the time, thought it was that so started eating breakfast again and it resolved), and had it again yesterday (early though, before breakfast).
Point being, I get this in a variety of ways, some has responded to HRT, some comes and goes as I move through this hormonal rollercoaster. (I’ve had other weird stuff that seems to last about 3 months and then goes away again). I guess if you’ve got a sensitive vestibular system it could be affected by fluctuating hormones in a variety of ways.
@Quickchantit could well be hormonal. Try some HRT and see if it improves?