This can happen right before, during or after menopause due to the change in hormones. One of my friends is going through this right now. She always had perfect BP and pulse and now it is whacked out. The doc told her that the drop in estrogen during / after "the change" affects this. He also told her that it isn't something you can use diet and exercise to control, it usually requires a low dose BP medicine, but that it is very common in women.