Hi. For The Last Several Months I Get Chills. Doesn't

Hi. For the last several months I get chills. Doesn't matter what the temp is inside the house or wherever I happen to be. The chills don't seem like normal chills where you get the chill bumps on your skin. These seem like it is more on the inside of my body. I have had fibromyalgia since 1993 but this not a symptom I have associated with it. My doctor checked thyroid and said it was ok. I am also extremely lethargic.