When you find out let me know! I'm going to be 52 in two months and I've had various degrees of these symptoms since about 45. They would come in waves. I'd have hot flahses for a while, wierd cycles, really light or really heavy (and I'm normally heavy - since I was a teen). Then everything would get normal for a while - sometimes for years. Then the hot flashes and weirdness would start again.
So for about the last 2 - 3 years I had nothing abnormal. My usual heavy cycle each month - a little more close together than it had ever been (I used to cycle in 33 days - then it became 30 days - almost exactly). Then this past December things changed. Very light periods, drenching night sweats, hot flashes that would absolutely melt me down - that would come and go 20 times a day. I attended client meetings with suit-jackets and sleeveless blouses so I could disrobe as needed. I didn't get my period for a couple of months - then a few days of light spotting. Sometimes black/dried looking - sometimes bright red. The only consistent thing is the inconsistency. The hot flashes have now subsided but now I have tender, swollen boobs. If I didn't have tied tubes I'd think I was PG again.
They say this perimenopausal time can go on for up to 10 years. I'm in about my 7th year now - but it has not been constant. Over the 7 years I've had about 12 months of symptoms - 3 months here, 2 months there, etc. They say you've completed menopause when you haven't had your cycle in a full year - so I've still got a year to go - minimum! Grrrrrrr.