Get a thermometer you know is accurate (Reli-On ones are cheap at the store, about $5). The minute you wake up, before you move, take your temp. Are you above 97? Then at about 2 or 3PM, take it again. Have you reached 98.x? If the answer is 'No' to both, get your thyroid checked.
I was the same way and did some investigating. I came across this:
http://tnation.t-nation.com/free_online_forum/sports_training_performance_bodybuilding_trt/thryroid_basics
Worked for me. People will tell you all day long that modern Western country's have plenty of iodine... I say "where"? I don't eat fish/kelp and used to use Sea Salt only sparingly. Avoiding all salt because of blood pressure is also recommended by docs...if those people don't eat fish/kelp, where is the iodine coming from? 150mcg from a multi isn't a lot when deficient. It's not in Milk or Bread anymore either.
I'm irresponsible, I just bought some IOPlus 12.5mg iodine/selenium tabs, quartered them, and took one on Mon, Wed, and Fri. Don't do that, go see a medical professional... after you read that thread
At the very least, a thermometer is a super cheap way to rule out thyroid issues.