98.6 is an average. Some people run high and some run low, naturally. My BBT is around 96.4 on average. Good luck!
Everybody is different, I agree. It wouldn't hurt to have your doctor check your thyroid. Especially if you have other symptoms... cold hands/feet, hair loss, acne. Even if medically your thyroid checks out, but you suffer from these symptoms, there are supplements that might help.
I take a drop of iodine everyday and it really helps.
Or you might just run a little cold.
I agree with rhireeder....check with your doctor to get your thyroid checked.