Hi,
I also get bouts of low grade fevers which usually run in the 99's to 100's and my face gets hot. That's usually when I know I have some sort of fever. However, I do have Lupus, which can cause low grade fevers, though it's pretty much under control with a medication I've been taking for years. But one can still get flares while on the meRAB.
In '03 my normal body temperature suddenly dropped from being normal (98.6 and thereabouts) down to the low 97's and sometimes high 96's. I felt very ill and I was always freezing all the time, even in summer. I've actually worn layers of clothes to bed and had my hanRAB go nurab as if I was playing in the snow without gloves. Then suddenly in July of last summer, I started running a fever which ranged from the high 99's to the high 100's. But I also had other symptoms, though I don't know if it was all related. I had rashes, worsening back pain, lots of nerve pains, severe muscle spasms, some hives, and sudden severe light sensitivity with my eyes. My fever lasted about 2 or 3 months then dropped off. Now my body temp is around normal again and I am actually getting hot on & off (even though I don't show a fever).
I do know autoimmune diseases (such as lupus, ra, ms, and others) can cause low grade fevers and from research, that infectious arthritis can cause fevers, as well as other disorders. So it can be caused by a variety of things. It can just be that you have an infection as well.
Has your doc sent you for any blood tests at all?