Peri is a very odd thing. I don't have any of the 'normal' symptoms, hence not prepared to accept it was that. No hot flashes, no night sweats, no sudden burst of anger, if anything, I've mellowed a lot! All my symptoms are neurologically related, in addition to the very poor sleep that is indeed common.
My mum didn't have these symptoms when she went through it, but she too had medical issues that would normally not be associated with the menopause at all (skin issues amongst other things).
Time will tell -and that's what I hold on to, just focusing on one day at a time- but I wouldn't be surprised is my symptoms were triggered by a number of things happening all at the same time, feeding off each other, hence making it hard to diagnosed.
Like you, I needed to eliminate possible diagnosis, including a brain tumour as my balance/dizziness were so bad at one point, and then along came the headaches. Thankfully MRI came back fine.
What is very odd and hard to explain is that I have a 'way' I feel that makes me feel miserable especially when it gets worse. It's a mixture of feeling very lightheaded, feeling weak and totally drained, really struggling to concentrate and feeling faint, with tinnitus in the mix. This is this feeling that at times got really bad, at which point my balance was affected, I couldn't stand being in a noisy room (even if it didn't feel that noisy to others), my heart rate would go up, it even affected my eye sight and I just felt absolutely dreadful.
This feeling is not completely gone and hits me most when I am involved in long conversations, meetings when I need to concentrate on what is said, and I still feel out of control and therefore a bit scared when it happens, but not half as bad as it used to be.
There is a sense of relief when results come back and are fine. The Lyme results were still not in last time I saw my GP a couple of weeks ago, I'm seeing him again next week so will ask, but I have kind of put it out of my mind. Indeed, its accuracy is not great, so that doesn't help, although I think I read it's more likely to be later rather than sooner after being infected.
Whatever the issue, don't let it lie and try to find answers, even though it's exhausting to do so.