I'm A 49 Yr Old Female. Fit, Slim -never Had

I'm a 49 yr old female. Fit, slim -never had to diet. Mother of 2 - youngest 11. Just hit menapause suddenly 3 months ago- horrid night sweats (3 months prior bloods showed no signs) All good other than last week I keep losing my balance. I suddenly hit the walls- lurching sideways. Or almost fall if I'm out. No dizzyness or feeling off. I just go off balance. I was running with the dogs today & almost fell over for no reason? What is happening to me??