Cold first 13 days of cycle

I am 45 and have monthly periods, but it is starting to come on earlier than it used to. One odd thing I've noticed is that I am freezing cold during the first half of my cycle and after ovulation, I feel warmer. I am hypothyroid and levels are good. My basal body temp is low 97's first half of cycle and 98 and over the second half. What is causing this temperature drop and what can I do to raise it? Do I need estrogen? I have several symptoms of estrogen deficiency, but from everything I read it seems that most women are estrogen dominant. Tweet