What Causes Excessive Sweating And Weakness In The Legs After Menopause?

I am 10 years post menopausal. At times, in cool building etc. I get what I call malignant sweats. I start to sweat and my hair becomes drenched, I become very weak, and my legs feel as though they are going to collapse. I do not feel faint. I have checked by glucose at the time of these episodes and it is normal. Any hints?