Clovey, I've noticed that I'm heavier DURING my period now, too.
I don't know if it has anything to do with the "Big Change". I'm in perimenopause, and I have NO idea what's going on with my body. Other than that I regularly have terrible night sweats. (and WHY I'm not losing weight from all that sweating is beyond me. It's like I've run a marathon during the night.)
I just console myself with the fact that the weight will go down again once my period has finished.