Persistent dizziness, nausea, weakness

I've read that some medications can cause this, so I'd ask your doctor about that, if you take medications. Your gp will probably have questions for you too.

Thank you for your answer.
I probably should have been more thorough. I don't take any medication. I was a perfectly healthy 28 year old until this started happening out of the blue.

Good then.
I'm no more help, but will read along. I'm sure this dizzyness business is difficult for you.

Thanks.
It's scary and I'm pretty sure I'm making it worse by stressing about it.
I have an appointment with my GP tomorrow. I'm just nervous and neeeded some support. So thank you

Ask about dehydration and sugar, too.

I get vasovagal response many days (it's just a fancy word for unexplained dizzy spells). I often can help myself by making sure I get enough water in a day (and not coffee or alcohol, sorry, as they both dehydrate you) and sometimes sugar.

Of course your doctor is the #1 go-to for you. But those might be at least a part of it.

I know a lot of how you feel (e. g. spinning bed, how nice. Not.). Hang in there.

Thanks.
It really can't be dehydration. I've always been drinking plenty of water. The sugar is fine too, according to my blood tests.
The biggest problem is that the neurologist ordered an MRI of the head, though she said she thinks the test will be normal, but there's a four month wait. It's gonna drive me crazy. This past week I've really been feeling sluggish. The dizziness has gotten worse to. I hope I can get some other tests done or the MRI sped up.

It sounds like you aren't in the US health system, which can be atrocious, but one can get an MRI here if going to the emergency room re your symptoms. I did a couple of years ago (my fainting/passing out turned out to be from the blood pressure pills). Coincidentally, I'd just read an article about that this morning.

Of course, then paying for the MRI can be a big problem in the U.S. some time after.

No, I'm from Europe. If I went to the emergency room by myself, they might do it immediately. But if a doctor refers you to something like that and marks it as not urgent, then the wait is horrible. I could pay for it myself and then they would take me in about a week. Lovely...
But as far as I know, it's worse in the US. In my country we have all this covered by pretty basic inssurance.