Hi JoH,
This sounds familiar to me, myself likely near post meno now, also running but had to cut back massively due to fatigue. It may be worth checking thyroid function, vitamin D etc also. I have been having spells of dizziness and nausea and this can be very tricky when having to go out to work and driving especially. Trying to keep some form of exercise even walking at times has helped me. HRT helps some people but I do seem to be not one of them. Wishing you all the best. AG