Wacky cycle with weight loss?

I have lost 45 pounds since May and been stalled for about 6 weeks. During that time my periods were a little closer together for awhile. Now suddenly my cycle is longer and the "girls" have been sore for a week. No, there is absolutely positively no way I'm pregnant. Anyone else had cycle fluctuations due to weight loss? I am also 43 so could it could be a combo with premebopause?