I generally run below normal...around 97.3. In the morning, first thing, it can be in the 96's. When I take it because I'm feeling kind of lousy and maybe feverish, it's usually around 98.8. If it progresses into the 99's I'm pretty sick - not something I wouldn't notice. From what I've read, it's good to take your temp for a couple weeks (with the same thermometer) about 3 times a day at regular intervals to get a feel for what is normal for you. Oftentimes a very low temp can indicate some thyroid problems, and could cause lots of other symptoms that make you feel crummy. I don't know what is up with the fluctuation - from what I understand that isn't something generally associated w/ fibro. Maybe you need to see a rheumatologist? I think inflammation will cause a low grade fever.
I too tend to run around 97.3-97.6. If I'm 98.6 it's unusual and into the 99s is a fever.
Has anyone ever checked you for Raynauds? It's a condition where the arteries narrow, restricting blood and causing hands, feet, nose, ears, etc to become cold and numb. It could just be your body not regulating itself well. And everyone's hands and feet will get cold when exposed. But if you're noticing a suspicious pattern I would definitely mention it to your doctor.
My norm is around 97. If I get a slight fever of 99 I feel like I'm really sick. I don't take my temp very often though.
I'm ALWAYS hot. But my feet and hands can't handle the cold at all. I have to wear gloves and extra socks if its any lower than 40 degrees.