tension headache + fever + nausea and wooziness

Hey everyone
For the past month I have just NOT been well... and Ive been to the doctor (2 of them) and neither one of them really knows whats going on and I'm starting to get desperate for any idea.

At the beginning of the month I had a horrible tension headache every day for a week, I went to the doctor, he told me he didnt know why, ordered an MRI, and everything came back ok, so he put me on fioricet- which I took for the first couple of days (its prescribed take as needed) and then havent taken much of it since.

The headaches started to go away... and then about 2 weeks ago... I got a fever. And I've had this fever every day since then. The weird thing is, I don't have any cold symptoms such as sore throat, stuffy nose, cough or anything. AND the fever doesnt spike or go about 100.6. It pretty much stays within the 99.5 area, though lately its been staying around the 100 area. My headaches randomly come back but now feel more like a sudden stabbing pain instead of a dull gradual ache. And then they go away on their own.

My only other symptoms are constipation and if I do any amount of real physical activity, nausea and wooziness.

I am late (period wise) but I've taken 3 different pregnancy tests and they all say negative. Also I was on birthcontrol pills for less than a month and stopped taking them last month because of the horrible side effects Ive had- so Ive been thinking that, along with stress may be the cause of my period being late.

I'm waiting on blood tests back, but even after we get those back, all it will do is deny or confirm that I have a bacterial infection and there will still be a lot of searching to be done. I was just wondering if anyone has any ideas as to what could be going on.

Im supposed to be leaving the state on a trip in a few days and now I'm afraid to since I don't know whats going on and how quickly it will get worse.