flucuating body temperature

Hello,

I have a very odd symptom that I can't seem to alleviate. Often times I get chills, especially at night, that cause me to shiver in bed. The air is not cold, I am dressed warmly, but I get the sensation of ice water running through my veins. Lately, this has started to happen in the afternoons too.

I'm pretty healthy, do liver and colon cleansing,use quality supplements, pure water, have gone through menopause, and don't have any real health issues except for a few extra pounds. In the past couple of months I have been taking some Grapefruit-Seed-Extract to combat a yeast infection, affecting my skin, but my temperature symptoms have been happening for at least 4 years, and there is nothing constistant about it.

Is this a thyroid issue? Any suggestions?

Aluna