What Causes On And Off Low Grade Fever Along With Dizziness And Tiredness?

Hi I've been having these low grade fevers on and off for at least 6 months now. I don't get them everyday and when I do have them, they aren't always present the whole day either! They range from 99.5 -101 degrees. When they started, I would get them a few days before my period so I thought it was just a weird hormonal thing. In august they even stuck around for over a week and I thought I might be pregnant, but it turned out I wasn't. Also my periods are very regular and I haven't had any problems in that arena. However, now it happens randomly, and every few weeks, and a few days at a time. My temp has been in the high 99 degrees range for the last three days now. The only other symptoms I've had are just some dizziness/disorientation and tiredness when I HAVE the fevers. Other than that, nothing out of the ordinary. I don't have a primary doc and to be honest I didn't want to make an appointment because I was afraid I would just be wasting their time. If the fevers get higher I'll definitely go in, but for now, I guess I'm just asking for an opinion :) THANK YOU!